- Email: [email protected]
2 Mutation Carriers
Accepted Manuscript Difference in Risk of Breast and Ovarian Cancer According to Putative Functional Domain Regions in Korean BRCA1/2 Mutation Carriers Ji Soo PARK, M.D., Seung-Tae LEE, M.D., Ph.D., Jung Woo HAN, M.D., Tae Il KIM, M.D., Ph.D., Eun Ji NAM, M.D., Ph.D., Hyung Seok PARK, M.D. PII:
S1526-8209(17)30785-1
DOI:
10.1016/j.clbc.2018.02.007
Reference:
CLBC 762
To appear in:
Clinical Breast Cancer
Received Date: 3 December 2017 Accepted Date: 10 February 2018
Please cite this article as: PARK JS, LEE S-T, HAN JW, KIM TI, NAM EJ, PARK HS, Difference in Risk of Breast and Ovarian Cancer According to Putative Functional Domain Regions in Korean BRCA1/2 Mutation Carriers, Clinical Breast Cancer (2018), doi: 10.1016/j.clbc.2018.02.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Type of Publication: Original Studies
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Title:
Difference in Risk of Breast and Ovarian Cancer According to Putative Functional Domain
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Regions in Korean BRCA1/2 Mutation Carriers
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Authors:
Ji Soo PARK, M.D.1 (E-mail: [email protected])
Seung-Tae LEE, M.D., Ph.D.1,2 (E-mail: [email protected])
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Jung Woo HAN, M.D.1,3 (E-mail: [email protected])
Tae Il KIM, M.D., Ph.D.1,4 (E-mail: [email protected])
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Eun Ji NAM, M.D., Ph.D.* 1,5 (E-mail: [email protected]) Hyung Seok PARK, M.D.* 1,6 (E-mail: [email protected]) These authors contributed equally to this work as corresponding authors.
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*
Affiliations: 1
Department of Hereditary Cancer Clinic, Cancer Prevention Center, Yonsei Cancer Center,
Yonsei University College of Medicine, Seoul, Korea
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Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea
3
Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
4
Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
5
Department of Obstetrics and Gynecology, Institute of Women’s Life Medical Science,
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2
Department of Surgery, Yonsei University College of Medicine, Seoul, Korea,
*Correspondence to: Prof. Eun Ji Nam, M.D., Ph.D.*
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6
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Women’s Cancer Clinic, Yonsei University College of Medicine, Seoul, Korea
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Department of Obstetrics and Gynecology, Institute of Women’s Life Medical Science, Women’s Cancer Clinic, Yonsei University College of Medicine, Seoul, Korea 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
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Tel: 82-2-2228-2230 / Fax: 82-2-313-8357
and
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E-mail: [email protected]
Prof. Hyung Seok Park, M.D.*
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Department of Surgery
50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea Tel: 82-2-2228-2100 / Fax: 82-2-313-8289
These authors contributed equally to this work as corresponding authors.
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*
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E-mail: [email protected]; [email protected]
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Yonsei University College of Medicine
Total number of Text pages: 26
Figures: 3
Disclosure:
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Supplementary figure: 1
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Tables: 4
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The authors declare no conflict of interest.
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ABSTRACT PURPOSE:
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We investigated the relative risk of breast and ovarian cancers related to the putative functional domain regions, obesity, and parity among Korean BRCA1/2 mutation carriers.
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PATIENTS AND METHODS:
We analyzed the clinical characteristics, cancer history, and mutations according to the putative
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functional domain of BRCA proteins among 229 women with BRCA1/2 mutations who were treated at Yonsei Cancer Center, Severance Hospital between January 2009 and March 2017. RESULTS:
Twenty-two carriers (18.8% of 117 BRCA1 mutation carriers) with mutations located in the
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BRCT domain region had a higher risk of breast cancers (hazard ratio [HR], 2.851; 95% confidence interval [CI], 1.614-5.039; P < 0.001) than those with mutations outside of the putative functional domains of BRCA1. The risk of ovarian cancer was increased in 13 of 112
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BRCA2 mutation carriers (11.6%), with mutations located on BRC repeat regions (HR, 3.129; 95%, 1.123-8.720; P = 0.029). The term-pregnancies number was a significant risk-reducing
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factor for breast cancers in BRCA1 mutation carriers (HR per pregnancy, 0.640; 95%, 0.5080.806; P < 0.001), for breast cancers in BRCA2 mutation carriers (HR per pregnancy, 0.534; 95%, 0.419-0.681; P < 0.001), and for ovarian cancers for BRCA1 mutation carriers (HR per pregnancy, 0.625; 95%, 0.474-0.824; P = 0.001). CONCLUSION:
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Among Korean women with the BRCA1/2 mutation, the location of the mutations may influence the risk of breast and ovarian cancers according to the putative functional domain regions.
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Further investigations are required for risk prediction and preventive strategies in the BRCA1/2 mutation carriers.
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Key words:
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BRCA; putative functional domain; BRCT; BRC repeats; parity; risk of cancer
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INTRODUCTION Germline mutations in BRCA1 or BRCA2 confer an increased risk of breast and ovarian cancers.
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In previous reports, individuals with BRCA1 and BRCA2 mutations had lifetime risks of 60-72% and 45-69% for breast cancer, respectively, and lifetime risks of 39-59% and 11-17% for ovarian cancer, respectively 1-3. Because of the significantly higher risks of breast and ovarian cancers in
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individuals with BRCA1 and BRCA2 mutations compared with those of general population,
preventive strategies have been considered for selected carriers; for examples, risk-reducing
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salpingo-oophorectomy (RRSO), risk-reducing mastectomy (RRM), tamoxifen, and oral contraceptives 4-6. However, invasive interventions may induce substantial adverse events, including sexual dissatisfaction, cardiovascular diseases, osteoporosis, postmenopausal symptoms followed by premature menopause, and psychological, financial, and/or cosmetic
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problems from RRM 7,8. Therefore, personalized cancer risk prediction was introduced for BRCA1/2 mutation carriers 9,10. This approach helps reduce the adverse event of invasive management and improves the effect of preventive strategies.
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Meanwhile, BRCA1 and BRCA2 proteins have several functional domains that bind to their unique binding partners. Some examples of highly active and conserved regions of BRCA1
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protein include the RING domain, which interacts with the BRCA1-associated RING domain protein 1 (BARD1); the BRCA1 C Terminus (BRCT) domain, which functions with its partner proteins abraxas, CtBP-interacting protein (CtIP), and BRCA1-interacting protein C-terminal helicase 1 (BRIP1); and coiled-coil domain, which binds to BRCA2 via PALB2 11. The BRCA2 proteins have DNA-binding domains (DBDs), which contain a helical domain, oligonucleotide binding (OB) folds, a tower domain, and eight BRC repeats combined with RAD51 11. In a
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recent large clinical study, the Consortium of Investigators of Modifiers of BRCA (CIMBA) reported the relative cancer risk of women with the BRCA1/2 mutation within the putative breast
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cancer cluster regions (BCCRs), ovarian cancer cluster regions (OCCRs), and functional domains 12. Among the carriers of BRCA1/2 mutations, breast and ovarian cancer risks were different according to the location of the specific mutations 12,13. In addition, non-genetic risk
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factors, including reproductive factors and body weight, were reported to possibly influence the occurrence of breast cancer 14,15. These findings can be used for risk prediction and cancer
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prevention of the carriers.
In this study, we evaluated the relative risks of breast cancer and ovarian cancer according to putative functional domain regions and clinical risk factors among Korean women with BRCA1/2
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germline mutations.
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MATERIAL AND METHODS Study population
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Between January 2009 and March 2017, 1,510 Korean women carrying at least one clinical feature of suspicious hereditary breast-ovarian cancer syndrome (HBOC) were evaluated for BRCA1 and BRCA2 germline mutation status in Yonsei Cancer Center, Severance Hospital,
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Seoul, Republic of Korea. The risk factors included the following: 1) a breast cancer patient with at least one first- or second-degree relative with breast and/or ovarian cancer; 2) a patient with
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breast cancer diagnosed before age 40; 3) a patient with bilateral breast cancer; 4) a breast cancer patient with other multiple primary cancers; 5) a patient with epithelial ovarian cancer; 6) a male breast cancer patient; and 7) a member of a family of known BRCA1/2 mutation carriers. Patients who met the following eligibility criteria were included in this study: 1) those who were
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known to be BRCA1/2 germline mutation carriers as proven by accepted methods; 2) those who were ≥19 years of age; and 3) those who were women. To analyze the breast and ovarian cancer risks according to locations of the mutations and reproductive factors, we defined the exclusion
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criteria as follows: 1) male mutation carriers; 2) patients with BRCA1/2 large intragenic
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rearrangement including deletions, duplication, or insertion of the exons; and 3) patients who already underwent bilateral salpingo-oophorectomy before the test of BRCA1/2 mutations, due to reasons other than ovarian cancer. We retrospectively reviewed the results of the medical records of the patients regarding BRCA1/2 germline mutation tests, clinicopathological features of breast and ovarian cancers, body mass index (BMI, kg/m2) at first visit to the clinic, parity, and termpregnancy number.
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We followed the medical research protocols and ethics guidelines defined by the World Medical Association’s Declaration of Helsinki throughout the study. The protocol was reviewed and
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approved by the local Institutional Review Board (IRB approval number: 4-2017-0521).
BRCA1 and BRCA2 genes analyses
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After extraction of genomic DNA from peripheral blood of the patients, the entire coding region
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(exon 2-23) and intron-exon boundaries (28 base pairs) of BRCA1 on chromosome 17q21 and the entire coding region (exon 2-27) and intron-exon boundaries (20 base pairs) of BRCA2 on chromosome 13q12.3 were amplified using polymerase chain reaction (PCR) amplification. The amplified products were directly sequenced using fluorescent dye-labeled sequencing primers. Genetic variants were analyzed by comparison with a consensus wild-type sequence of each
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gene (NM_007294.3 for BRCA1 and NM_000059.3 for BRCA2). We classified the deleterious genetic variants by introducing premature termination codons through frameshift, nonsense, and splice junction alterations as pathogenic variants, which were referred to as ‘mutations’ in this
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study. Most variant of unknown significance (VUS) included missense mutation, small in-frame
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deletions and insertions, synonymous substitution, alteration in non-coding intervening sequences (IVS), or untranslated exonic regions (UTRs).
Nomenclature system of variants
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We followed the Human Genome Organisation (HUGO)-approved nomenclature system of the Human Genome Variation Society (http://www.hgvs.org/mutnomen) for description of the
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variants.
Putative functional domain regions
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We defined the risk group in this study as the carriers with pathogenic variants located on the
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following putative functional domains: RING, coiled-coil, and BRCT domains of BRCA1; and BRC repeats, helical, OB-folds, and tower domains of BRCA2. The locations of putative functional domains were defined using the boundaries in the Pfam database 16. We used the carriers with mutations outside of the putative functional domains as a reference group to
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estimate the relative risks of breast and ovarian cancers of the risk group.
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To estimate the influence of obesity on the risk of breast/ovarian cancers in BRCA1/2 mutation carriers, we collected the BMIs of the patients at each patient’s first visit to our clinic, and
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divided the BMIs into the following four categories according to the World Health Organization (WHO) definition of obesity and overweight for the Asian population: underweight, <18.5 kg/m2; normal, ≥18.5 kg/m2 and <23 kg/m2; overweight, ≥23 kg/m2 and <25 kg/m2; obese, ≥25 kg/m2 17. Parity indicates the number of pregnancies reaching viable gestational age, including viable births and stillbirths, and term-pregnancy was defined as ‘a pregnancy resulting in a delivery that occurs between 37 weeks 0 days and 41 weeks 6 days’ 18.
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Statistical analyses
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The cumulative incidences of breast/ovarian cancers in BRCA1/2 mutation carriers were
analyzed using the Kaplan-Meier method, and survival curves were compared using log-rank tests. We used Pearson’s χ2 tests, Mann-Whitney U tests, and linear regression analyses to
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evaluate the clinicopathological differences between the carriers with BRCA1 and BRCA2
mutations. The relative risks of breast cancer and ovarian cancers in the carriers with a BRCA1/2
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mutation in putative functional domains were estimated using Cox’s proportional hazard regression model. In the Cox regression model, BMI and reproductive factors were also used, with the putative functional domain regions as covariates. A P-value of <0.05 was considered statistically significant. All statistical analyses were performed using SPSS 23 for Windows
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(IBM, Armonk, NY, USA)
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RESULTS Patient characteristics
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Among the 1,510 Korean women with BRCA1/2 germline mutation who were evaluated, 250 subjects (16.6%; 128 subjects with BRCA1 mutations and 122 subjects with BRCA2 mutations) had one of 97 kinds of deleterious mutations, and the other 255 patients (16.9%) had VUS only.
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Of the 250 BRCA1/2 mutation carriers, we excluded 12 men, five carriers with large
rearrangement of exons in BRCA1/2 genes (all patients had large exonic deletions), and four
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carriers who had already received bilateral salpingo-oophorectomy due to reasons other than ovarian cancer. Finally, 117 cases with BRCA1 mutations and 112 cases with BRCA2 mutations
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were included in this analysis (Fig S1).
Clinicopathological features of BRCA1/2 mutation carriers There were 116 patients with breast cancer, 53 patients with ovarian cancer, 31 patients with
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both breast and ovarian cancers, and 29 unaffected carriers. All the carriers were followed up until the median age of the group (50.8 years; range, 21.1-84.1 years), and no one received
tests.
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prophylactic mastectomy or salpingo-oophorectomy before they underwent BRCA1/2 genetic
Among 147 patients who had been diagnosed with breast cancer, there was no difference between the patients with BRCA1 and BRCA2 mutations in the ages at diagnosis of first breast cancer, literalities, and histological features. Subtypes of breast cancers varied between BRCA1 and BRCA2 carriers; specifically, BRCA1 mutation carriers had more triple negative breast
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cancers (TNBCs; 71.6%), and BRCA2 mutation carriers had more estrogen receptor (ER)positive breast cancer (62.4%). Among the 84 patients with ovarian cancers, there were no
between BRCA1 and BRCA2 mutation carriers (Table 1).
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differences in the ages at diagnosis of ovarian cancers and histologic features of ovarian cancers
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Cumulative incidence of breast cancer and ovarian cancer in BRCA1/2 mutation carriers
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Among the 117 BRCA1 mutation carriers, 70 (59.8%) were diagnosed with breast cancer at the median age of 49.9 years (95% confidence interval [CI], 43.9-55.9) Among the 112 BRCA2 mutation carriers, 77 (68.8%) were diagnosed with breast cancer at the median age of 46.8 years (95% CI, 44.0–49.6). The hazard ratio (HR) of cumulative incidence in BRCA1 mutation carriers
0.164) (Fig 1A).
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[BRCA1mut] versus BRCA2 mutation carriers [BRCA2mut] was 0.794 (95% CI = 0.573–1.100; P =
In addition, 60 of 117 (51.3%) BRCA1 mutation carriers were diagnosed with ovarian cancer at
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the median age of 56.5 years (95% CI, 53.3–59.7). The cumulative risk of ovarian cancers in the carriers with BRCA1 mutations was significantly higher than that in the carriers with BRCA2
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mutations (24 of 112 carriers [21.4%]; median age, 60.7 years; 95% CI, 58.5–63.0; HR of cumulative incidence in BRCA1mut versus BRCA2mut, 2.252; 95% CI, 1.400–3.624; P = 0.001) (Fig 1B).
Frequency of the mutations located at putative functional domain regions in BRCA1/2
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Among 117 carriers with BRCA1 mutations, we found six (5.1%) mutations located on the serine-rich domain, two (1.7%) mutations on the coiled-coil domain, and 22 (18.8%) mutations
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on the BRCT domain. Among 112 carriers with BRCA2 mutations, there were 13 (11.6%) mutations on BRC repeats, 21 (18.8%) mutations on the helical domain, and three (2.7%)
mutations on the OB-fold domain. No mutations were found on the RING domain of BRCA1
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and the tower domain of BRCA2 (Table 2 and Fig 2).
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Relative risk related to the occurrence of breast and ovarian cancers in BRCA1/2 mutation carriers according to putative functional domains, obesity, and term-pregnancy number Among the carriers with BRCA1 mutations, deleterious mutations resulting in changes of amino acids located on the BRCT domain [BRCA1mut-BRCT] were correlated with a higher risk of breast
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cancers than mutations outside of the putative functional domain regions [BRCA1mut-ref] (p.1643– 1723 and p.1756–1842; HR, 2.851; 95% CI, 1.614–5.039; P < 0.001). In addition, the risk of breast cancer was reduced with the increase in term-pregnancy number (HR per each pregnancy,
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0.640; 95%, 0.508–0.806; P < 0.001) (Table 3). Among the carriers with BRCA2 mutations, the
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risk of ovarian cancer was correlated with BRC repeats of BRCA2 (p.1003–1035, p.1213–1245, p.1422–1454, p.1518–1550, p.1665–1696, p.1838–1869, p.1973–2004, and p.2052–2084; HR versus mutations outside of putative functional domain regions [BRCA2mut-ref], 3.129; 95% CI, 1.123–8.720; P = 0.029) (Table 4). In addition, the term-pregnancy number was a significant risk-reducing factor for breast cancers in BRCA2 mutations carriers (HR per each pregnancy, 0.534; 95% CI, 0.419–0.681; P < 0.001)
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(Table 4) and ovarian cancers in BRCA1 mutations carriers (HR per each pregnancy, 0.625;
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95%CI, 0.474–0.824; P = 0.001) (Table 3).
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DISCUSSION In the present study, we analyzed risk factors (putative functional domain regions, obesity, and
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term-pregnancy number) related to cumulative incidences of breast and ovarian cancer among Korean women with BRCA1/2 germline mutations. We found that BRCT domain regions were associated with increased risk of breast cancers among BRCA1 mutation carriers, and BRC
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repeats regions were associated with increased risk of ovarian cancers among BRCA2 mutation carriers. Furthermore, the term-pregnancy number was related to decreased risk of breast cancer
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among BRCA1/2 mutation carriers and ovarian cancer among BRCA1 mutation carriers. The pathological characteristics of the carriers with BRCA1/2 mutations were consistent with previous reports 19. However, because most of the participants (88.3%) of this study were affected carriers, the cumulative risks of breast and ovarian cancers may be overestimated
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(cumulative risks of breast cancer up to age 70 years were 83% among BRCA1 mutation carriers and 86% among BRCA2 mutation carriers; cumulative risks of ovarian cancer up to age 70 years were 89% among BRCA1 mutation carriers and 66% among BRCA2 mutation carriers) compared
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to those in a recent clinical study of a large population including affected and unaffected carriers (67% and 66% cumulative risk of breast cancer and 45% and 12% cumulative risk of ovarian
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cancer in BRCA1 and BRCA2 mutation carriers aged 80 years, respectively) 20. The discordance of these studies may be mainly due to different study populations, which needs to be considered when interpreting the results. The cumulative risks of breast and ovarian cancers of the study may be primarily influenced by the affected carriers, with potential risk factors like putative functional domain regions, obesity, and term-pregnancy number, and not by the unaffected carriers.
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Rebbeck et al. suggested that the risk of breast cancer was significantly higher in the carriers with mutations in the BRCT domains and lower in the carriers with mutations in BRC repeats.
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They also reported co-locations between BRCT domains and putative BCCR2’ (c.5261–5563), and between BRC repeats and putative OCCR1 (c.3249–5681, and c.5946) 12. Kuchenbaecker et al. reported that age-specific risks of breast cancer were increased in the carriers with mutations
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outside c.2282–4071 in BRCA1 and c.2831–6401 in BRCA2 13. Our results were consistent these previous reports. In addition, the risk of ovarian cancer was significantly increased in the carriers
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with the mutations at BRC repeats regions in BRCA2. The BRC repeats in BRCA2 are known to bind to RAD51, which is an essential recombinase enzyme for repair DSB in DNA by homologous recombination 21,22. Therefore, BRCA2 with mutations at BRC repeats were possibly defective in recruiting RAD51 to the sites of DSB and, as a result, may affect cancer susceptibility 21. Moreover, there is clinical evidence that the carriers with deleterious mutations
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in RAD51C and RAD51D had significantly increased risks of ovarian cancers 23. Further clinical research and functional studies will help clarify the cancer risk and the its mechanisms by
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mutations of BRC repeats at BRCA2 protein.
In a previous study, we found that the missense variant of BRCA1 c.5339T>C (p.Leu1780Pro;
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rs80357474) is a pathogenic mutation in Korean patients according to American College of Medical Genetics and Genomics (ACMG) standards and guidelines for interpreting sequence variants 24. Because BRCA1 Leu1780 was located at the C-terminal end of the BRCT domain, the replacement of leucine with proline and following changes in structures had been predicted to cause a higher risk of disease 25. In comparison with the carriers with other known deleterious mutations located at BRCT domains or BRCA1mut-ref, the relative risk of breast cancer among the carriers of BRCA1 Leu1780Pro have not been estimated. Among 1,510 patients in this study, we
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found 13 patients with BRCA1 Leu1780Pro, who were not included in the 250 patients with known deleterious mutations. Among the 13 carriers with BRCA1 Leu1780Pro, 11 carriers were
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diagnosed with breast cancers at the median age of 38.4 years (95% CI, 33.9–42.9). By comparison, 18 of 22 patients with BRCA1 mutations located at BRCT domains were diagnosed with breast cancers at a median age of 39.0 years (95% CI, 35.1–42.9) years of age. The age at
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diagnosis of breast cancer was not significantly different between patients with Leu1780Pro and those with known deleterious mutations located on BRCT domain (P = 0.885). However, age at
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diagnosis of breast cancer in patients with mutations at BRCT domain was significantly earlier than those with BRCA1mut-ref (median, 51.0; 95% CI, 45.0–57.0; P = 0.012) (Fig 3). This result indicates that BRCA1 mutations located at BRCT domain regions were associated with early onset of breast cancer. In addition, onset of breast cancer among the carriers with BRCA1
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Leu1780Pro is similar to those of the carriers with BRCA1 mutations located at BRCT domains. Because hormonal exposure is significantly correlated with occurrence of breast cancer in women, several reproductive factors (e.g., early menarche, late menopause, nulliparity, and no
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breastfeeding) have been studied as potential strong risk factors for women to develop breast cancer. A previously published meta-analysis showed that multiparity with more than three live
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births is associated with reduced risk of breast cancer in BRCA1/2 mutation carriers, and multiparity with more than four live births is related to decreased risk of ovarian cancer in BRCA1 mutation carriers 26. In this study, parous (with any live birth) women had significantly lower risks of breast cancer than nulliparous women among BRCA1 mutations carriers (HR, 0.367; 95% CI, 0.207–0.650; P = 0.001), and among BRCA2 mutation carriers (HR, 0.233; 95% CI, 0.134–0.404; P<0.001), and lower risk of ovarian cancers among BRCA1 mutation carriers (HR, 0.368; 95% CI, 0.172–0.786; P = 0.010). We also found a significant increase trend in the
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term-pregnancy number, and a reduced risk of development of breast and ovarian cancers. These factors related to estrogen exposure, including hormone replacement therapy, parity, and number
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of child-bearing pregnancies, are partially modifiable in the carriers. Therefore, future research and adequate application to clinics are required for preventive strategies to treat carriers with BRCA1/2 mutations.
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Obesity is another well-known risk factor of breast cancer. However, the results of this study did not show a significant correlation between obesity and the risk of breast cancer. This result is
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possibly due to the different standards of obesity in the Asian population and the relatively higher proportion of premenopausal women with breast cancer among Korean BRCA1/2 mutation carriers. A WHO expert consultation addressed the issue that a stricter BMI was recommended for Asian populations compared with European populations. Because Asian
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people have a high risk of type 2 diabetes mellitus and cardiovascular diseases at BMIs lower than the WHO cut-off point for being overweight (≥ 25 kg/m2), BMI cut-off points should be redefined for Asian population separately 17. Interestingly, the epidemiologic studies showed that
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BMI of ≥ 25 kg/m2 is not associated with excess risk of death from any cause of death in the Asian population. Rather, being underweight is related to increased risk of death in all Asian
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populations 27, and Korean patients with a BMI of 23.0–24.9 kg/m2 have the lowest risk of death from any cause 28. Thus, there is a need to establish new standards for overweight and obesity in Korean populations. The strict standard of normal BMI (≥18.5 to <23 kg/m2), resulting in classification of more women as overweight or obese, possibly influenced the analysis of the relationship between breast cancer risk and obesity in Korean BRCA1/2 mutation carriers. Another reason that obesity did not influence the relative risk of breast cancer in Korean populations is that obesity has a strong association with estrogen receptor-positive breast cancers
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in postmenopausal women 29. In contrast, breast cancers with BRCA1/2 mutations occur in young, premenopausal women 30,31, and most breast cancers present as estrogen receptor-negative types
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among BRCA1 mutation carriers 19,31. In addition, body weight is not static but can change by one’s lifestyle. A reference point of obesity in an individual life and long-term follow-up is needed for accurate analyses.
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There are several limitations to this study. Because of the small number of carriers, cancer risks related to several putative functional domain regions could be underestimated. Other known risk
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factors, including reproductive factors (age at menarche, breast feeding, oral contraceptive, and hormone replacement therapy), physical activity, alcohol consumption, smoking, and early radiation exposure were not evaluated due to lack of data in the medical records. Despite these limitations, to the best of our knowledge, this is the first study analyzing the risk of
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breast and ovarian cancer according to putative functional domain regions in Korean BRCA1/2 mutation carriers, with adjustment for other well-known risk factors like obesity and termpregnancy number. We will analyze the relative cancer risks according to functional domains in
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multi-center large clinical database in Korea.
CONCLUSION
We suggest that mutations according to putative functional domains of BRCA proteins may influence risk and onset time of breast and ovarian cancers in BRCA1/2 mutation carriers. Understanding the landscape regarding mutations in functional domain regions may provide meaningful insights into cancer risks and preventive strategies among Korean women with BRCA1/2 mutations.
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SHORT CLINICL PRACTICE POINT Germline mutations in BRCA1 or BRCA2 confer an increased risk of breast and ovarian
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cancers. Although clinical guidelines recommend preventive strategies including riskreducing salpingo-oophorectomy (RRSO), risk-reducing mastectomy (RRM), tamoxifen, and oral contraceptives, invasive interventions may induce substantial adverse events.
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In this study, we suggested that the locations of BRCA1/2 mutation affected the risk of breast and ovarian cancers. Higher cancer risk was related to BRCT domain of BRCA1
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for breast cancer, and BRC repeats of BRCA2 for ovarian cancer.
We also found that parity was a risk-reducing factor for breast cancer among BRCA1/2 mutation carriers, and for ovarian cancer among BRCA1 mutation carriers.
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These risk factors will be applied to predict occurrence and cumulative risk of cancer of each carrier. Personalized prediction of breast and ovarian cancer risks will be used to reduce adverse events of invasive management and improve the efficacy of preventive
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strategies for BRCA1/2 mutation carriers.
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Acknowledgements
The results of this study were presented as part of the 24th Asia Pacific Cancer Conference (APCC) held on June 22nd–24th, 2017, Seoul, Republic of Korea. The authors thank Bio Science Writers (http://www.biosciencewriters.com/) for English language editing service.
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Funding This research did not receive any specific grant from funding agencies in the public, commercial,
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or not-for-profit sectors.
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Figure legends
Fig 1. Differences in cumulative incidence of breast and ovarian cancer between BRCA1 and
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BRCA2 mutation carriers: (A) breast cancer; (B) ovarian cancer.
Fig 2. Locations with frequency of the mutations according to putative function domains: (A) BRCA1; (B) BRCA2.
Fig 3. Cumulative incidences of breast cancers among the carriers with BRCA1 mutations
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located at BRCT domain, L1780P, and outside of putative functional domain.
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Oncology: Genetics/ Familial High-Risk Assessment: Breast and Ovarian (Version 2.2017) https://www.nccn.org/professionals/physician_gls/pdf/genetics_screening.pdf.
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Accessed 01 Jul 2017.
Paluch-Shimon S, Cardoso F, Sessa C, et al. Prevention and screening in BRCA mutation
carriers and other breast/ovarian hereditary cancer syndromes: ESMO Clinical Practice Guidelines for cancer prevention and screening Ann Oncol 2016; 27:v103-v10.
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Parker WH, Jacoby V, Shoupe D, et al. Effect of bilateral oophorectomy on women's long-term health Womens Health (Lond) 2009; 5:565-76.
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Boughey JC, Attai DJ, Chen SL, et al. Contralateral Prophylactic Mastectomy Consensus Statement from the American Society of Breast Surgeons: Additional Considerations and
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a Framework for Shared Decision Making Ann Surg Oncol 2016; 23:3106-11. Antoniou AC, Cunningham AP, Peto J, et al. The BOADICEA model of genetic
susceptibility to breast and ovarian cancers: updates and extensions Br J Cancer 2008;
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98:1457-66.
Kuchenbaecker KB, McGuffog L, Barrowdale D, et al. Evaluation of Polygenic Risk
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Scores for Breast and Ovarian Cancer Risk Prediction in BRCA1 and BRCA2 Mutation Carriers J Natl Cancer Inst 2017; 109. 11.
Roy R, Chun J, Powell SN. BRCA1 and BRCA2: different roles in a common pathway of genome protection Nat Rev Cancer 2011; 12:68-78.
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Rebbeck TR, Mitra N, Wan F, et al. Association of type and location of BRCA1 and
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BRCA2 mutations with risk of breast and ovarian cancer JAMA 2015; 313:1347-61. Kuchenbaecker KB, Hopper JL, Barnes DR, et al. Risks of Breast, Ovarian, and
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Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers JAMA 2017; 317:2402-16.
Levy-Lahad E, Friedman E. Cancer risks among BRCA1 and BRCA2 mutation carriers
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Br J Cancer 2007; 96:11-5.
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Toss A, Grandi G, Cagnacci A, et al. The impact of reproductive life on breast cancer risk in women with family history or BRCA mutation Oncotarget 2017; 8:9144-54.
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Finn RD, Coggill P, Eberhardt RY, et al. The Pfam protein families database: towards a more sustainable future (http://pfam.xfam.org/ ) Nucleic Acids Res 2016; 44:D279-85.
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Consultation WHOE. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies Lancet 2004; 363:157-63. Spong CY. Defining "term" pregnancy: recommendations from the Defining "Term"
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Pregnancy Workgroup JAMA 2013; 309:2445-6. 19.
Mavaddat N, Barrowdale D, Andrulis IL, et al. Pathology of breast and ovarian cancers
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among BRCA1 and BRCA2 mutation carriers: results from the Consortium of
Investigators of Modifiers of BRCA1/2 (CIMBA) Cancer Epidemiol Biomarkers Prev
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2012; 21:134-47.
Hartmann LC, Lindor NM. The Role of Risk-Reducing Surgery in Hereditary Breast and Ovarian Cancer N Engl J Med 2016; 374:454-68.
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Pellegrini L, Yu DS, Lo T, et al. Insights into DNA recombination from the structure of a RAD51-BRCA2 complex Nature 2002; 420:287-93.
Carreira A, Hilario J, Amitani I, et al. The BRC repeats of BRCA2 modulate the DNA-
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binding selectivity of RAD51 Cell 2009; 136:1032-43. Song H, Dicks E, Ramus SJ, et al. Contribution of Germline Mutations in the RAD51B,
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RAD51C, and RAD51D Genes to Ovarian Cancer in the Population J Clin Oncol 2015;
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33:2901-7.
Park JS, Nam EJ, Park HS, et al. Identification of a Novel BRCA1 Pathogenic Mutation in Korean Patients Following Reclassification of BRCA1 and BRCA2 Variants According to the ACMG Standards and Guidelines Using Relevant Ethnic Controls
Cancer Res Treat 2017.
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Lee MS, Green R, Marsillac SM, et al. Comprehensive analysis of missense variations in the BRCT domain of BRCA1 by structural and functional assays Cancer Res 2010;
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70:4880-90. Friebel TM, Domchek SM, Rebbeck TR. Modifiers of cancer risk in BRCA1 and BRCA2 mutation carriers: systematic review and meta-analysis J Natl Cancer Inst 2014;
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106:dju091.
Zheng W, McLerran DF, Rolland B, et al. Association between body-mass index and risk
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Jee SH, Sull JW, Park J, et al. Body-mass index and mortality in Korean men and women N Engl J Med 2006; 355:779-87.
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of death in more than 1 million Asians N Engl J Med 2011; 364:719-29.
Neuhouser ML, Aragaki AK, Prentice RL, et al. Overweight, Obesity, and Postmenopausal Invasive Breast Cancer Risk: A Secondary Analysis of the Women's
30.
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Health Initiative Randomized Clinical Trials JAMA Oncol 2015; 1:611-21. Kim H, Cho DY, Choi DH, et al. Characteristics and spectrum of BRCA1 and BRCA2
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mutations in 3,922 Korean patients with breast and ovarian cancer Breast Cancer Res Treat 2012; 134:1315-26.
Yu JH, Lee JW, Son BH, et al. Characteristics of BRCA1/2 Mutation-Positive Breast
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Cancers in Korea: A Comparison Study Based on Multicenter Data and the Korean Breast Cancer Registry J Breast Cancer 2014; 17:129-35.
Table 1. Baseline characteristics
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41.9 (22.6-71.8)
41.6 (22.2-81.0)
0.278*
61 16
79.2% 20.8%
113 34
76.9% 23.1%
0.479
58 5 1 17 12
62.4% 5.4% 1.1% 18.3% 12.9%
71 5 1 80 24
39.2% 2.8% 0.6% 44.2% 13.3%
<0.001†
74 6 1 1 6 5
79.6% 6.5% 1.1% 1.1% 6.5% 5.4%
149 7 2 1 11 11
82.3% 3.9% 1.1% 0.6% 6.1% 6.1%
0.435†
P-value <0.001
55.2 (46.5-71.7)
53.7 (28.7-78.7)
0.120*
19 1 0 1 1 1
69 1 2 3 1 8
0.109†
82.8% 4.3% 0% 4.3% 4.3% 4.3%
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Breast cancer Ovarian cancer Breast and ovarian cancer Unaffected carrier Breast cancer (N=147) Age at diagnosis [years, median] (range) 40.8 (22.2-81.0) Laterality Unilateral 52 74.3% Bilateral 18 25.7% Subtype (total of first and secondary breast cancers, N=181) ER+ 13 14.8% ER+/HER2+ 0 0% HER2+ 0 0% TNBC 63 71.6% unknown 12 13.6% Histology (total of first and secondary breast cancers, N=181) IDC 75 85.2% DCIS 1 1.1% ILC 1 1.1% LCIS 0 0% others 5 5.8% unknown 6 6.8% Ovarian cancer (n=84) Age at diagnosis [years, median] (range) 52.9 (28.7-78.7) Histology Serous carcinoma 49 81.7% Mucinous carcinoma 0 0% Endometrioid carcinoma 2 3.3% Poorly differentiated 2 3.3% others 0 0% unknown 7 11.7%
Total (N=229) Number % 116 50.7% 53 23.1% 31 13.5% 29 12.7%
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Type of cancer
BRCA2 mutation carriers (N=112) Number % 69 61.6% 16 14.3% 8 7.1% 19 17.0%
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BRCA1 mutation carriers (N=117) Number % 47 40.2% 37 31.6% 23 19.7% 10 8.5%
82.1% 1.2% 2.4% 3.6% 1.2% 9.5%
Abbreviations: DCIS, ductal carcinoma in situ; ER, estrogen receptor; HER2, human epidermal growth factor 2; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; LCIS, lobular carcinoma in situ; N, number; TNBC, triple negative breast cancer. Key: (*) analyzed using the
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Mann-Whitney U test; (†) analyzed using the Fisher’s exact test.
Table 2. Frequency of mutations according to the putative functional domain of BRCA1 and BRCA2
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Coiled Coil
2
1.7%
BRCT
22
18.8%
87
74.4%
Effect on amino acids
Type
c.1288C>T c.1471C>T c.1480C>T c.1511dupG c.3813dupT c.4253delT c.5030_5033delCTAA c.5075-2A>G c.5080G>T c.5266dupC c.5333-2A>T c.5445G>A c.5496_5506delGGTGACCCGAGinsA c.5511G>A c.213-1G>A c.302-2A>C c.302-1G>C c.390C>A c.928C>T c.922_924delAGCinsT c.1016dupA c.1630C>T c.1716delA c.1729G>T c.1823delA c.1831delC c.2048delA c.2345delG c.2354T>A c.2433delC c.3228_3229delAG c.3277delG c.3296delC c.3340G>T c.3442delG c.3627dupA c.3895C>T c.3954dupT c.4041_4042delAG c.4092_4093delCT c.4120_4121delAG c.4127_4128delCA c.4286_4290delACCCT c.4327C>T c.4335_4338dupAGAA c.4485-2A>G c.5194-2A>G c.5260G>T
p.Gln430Ter p.Gln491Ter p.Gln494Ter p.Lys505Terfs p.Asn1272Terfs p.Leu1418Ter p.Thr1677Ilefs
p.Glu1754Ter
NS NS NS FS FS NS FS S NS FS S NS FS NS S S S NS NS FS FS NS FS NS FS FS FS FS NS FS FS FS FS NS FS FS NS FS FS FS FS FS FS NS FS S S NS
n 0 1 1 1 3 1 1 2 1 5 1 1 3 8 1 1 1 2 14 1 9 3 1 1 1 1 1 1 3 3 2 1 1 2 4 5 14 2 1 1 2 2 1 1 1 1 1 1 1
Genetic variant (DNA level) c.3096_3110delAGATATTGAAGAACAinsT c.5576_5579delTTAA c.5590_5593delGACA c.7480C>T
Effect on amino acids p.Lys1032Asnfs p.Ile1859Lysfs p.Asp1864Tyrfs p.Arg2494Ter
Type FS FS FS NS
n 1 11 1 21
p.Glu1694Ter p.Gln1756Profs
p.Trp1815Ter p.Val1833Serfs p.Trp1837Ter
p.Tyr130Ter p.Gln310Ter p.Ser308Terfs p.Val340Glyfs p.Gln544Ter p.Glu572Aspfs p.Glu577Ter p.Lys608Argfs p.Leu611Terfs p.Lys683Serfs p.Ser782Ilefs p.Leu785Ter p.Lys812Argfs p.Gly1077Alafs p.Val1093Serfs p.Pro1099Leufs p.Glu1114Ter p.Glu1148Argfs p.Glu1210Argfs p.Gln1299Ter p.Gly1319Trpfs p.Gly1348Asnfs p.Leu1365Argfs p.Ser1374Terfs p.Thr1376Lysfs p.Tyr1429Phefs p.Arg1443Ter p.Gln1447Argfs
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Other
Genetic variant (DNA level)
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BRCA1 functional domains (n=117) Domain n (domain) % RING 0 0% Serine-rich 6 5.1%
BRCA2 functional domains (n=112) Domain n (domain) % BRC repeats 13 11.6%
DNA binding: helical DNA binding: OB folds DNA binding: Tower Others
21
18.8%
3
2.7%
c.8002_8008dupAGAAGAT c.9253delA c.9254_9256+11del
p.Ser2670Terfs p.Thr3085Glnfs
FS FS S
1 1 1 0
66.9%
c.276dupA c.370delA c.475+1G>T c.516+1G>A c.632-1G>T c.755_758delACAG c.800delG c.994delA
p.Ser93Ilefs p.Met124Trpfs
FS FS S S S FS FS FS
1 2 1 1 1 2 2 2
0 75
p.Asp252Valfs p.Gly267Glufs p.Ile332Phefs
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c.1309_1312delAAAG p.Lys437Ilefs c.1399A>T p.Lys467Ter ACCEPTED MANUSCRIPT c.1495C>T p.Gln499Ter c.1794_1798delATCTT p.Ser599Terfs c.2130_2131insAA p.Cys711Asnfs c.2376C>A p.Tyr792Ter c.2588dupA p.Asn863Lysfs c.2683_2684dupGC p.Asn896Leufs c.2786T>G p.Leu929Ter c.2798_2799delCA p.Thr933Argfs c.2808_2811delACAA p.Ala938Profs c.3170_3174delAGAAA p.Lys1057Thrfs c.3744_3747delTGAG p.Ser1248Argfs c.3837delT p.Asn1279Lysfs c.4372delC p.His1458Ilefs c.4471_4474delCTGA p.Leu1491Lysfs c.5699C>G p.Ser1900Ter c.6428C>A p.Ser2143Ter c.6437_6440delATCA p.Asn2146Thrfs c.6600_6601delTT p.Ser2201Terfs c.6952C>T p.Arg2318Ter c.7368_7371delGTTT p.Phe2457Thrfs c.7375A>T p.Lys2459Ter c.8488-1G>A c.8991T>G p.Tyr2997Ter c.9018C>A p.Tyr3006Ter c.9076C>T p.Gln3026Ter c.9105T>G p.Tyr3035Ter Abbreviations: BRCT, BRCA1 C Terminus; FS, frameshift; NS, nonsense; S, splicing; OB, oligonucleotide binding.
FS NS NS FS FS NS FS FS NS FS FS FS FS FS FS FS NS NS FS FS NS FS NS S NS NS NS NS
2 14 1 2 2 2 1 2 1 4 5 1 4 2 1 2 1 1 1 1 1 2 1 1 1 1 5 1
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Table 3. Breast and ovarian cancer risks related to risks factors among BRCA1 mutation carriers Parameter
Breast cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
Ovarian cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
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NTotal NAffected % NAffected % Proportion of 117 70 59.8% 59 50.4% affected carrier Functional domains RING 0 0 0 N/A N/A 0 0 N/A N/A Serine-rich 6 1 16.7% 0.453 (0.062-3.285) 0.433 0.421 (0.056-3.146) 0.399 3 50.0% 3.015 (0.913-9.963) 0.070 3.210 (0.901-11.43) 0.072 2 100% 0.609 (0.146-2.546) 0.497 0.949 (0.122-7.361) 0.960 Coiled Coil 2 1 50% 0.605 (0.083-4.319) 0.619 N/A BRCT 22 18 81.8% 1.865 (1.080-3.222) 0.025 2.851 (1.614-5.039) <0.001 10 45.5% 0.692 (0.345-1.390) 0.301 1.171 (0.570-2.407) 0.667 Other 87 50 57.5% 1 1 44 50.6% 1 1 BMI (kg/m2) [n=114] Median, 22.8 (range, 15.7-39.4) Normal 54 34 63.0% 1 1 24 44.4% 1 1 (≥18.5 to <23) Underweight 5 3 60.0% 1.205 (0.368-3.945) 0.758 1.300 (0.391-4.324) 0.669 3 60.0% 1.930 (0.572-6.514) 0.289 1.065 (0.302-3.750) 0.922 (<18.5) Overweight 17 10 58.8% 0.534 (0.262-1.088) 0.084 0.577 (0.278-1.196) 0.139 11 64.7% 0.523 (0.253-1.078) 0.079 0.505 (0.238-1.070) 0.075 (≥23 to <25) 38 22 57.9% 0.805 (0.469-1.382) 0.431 0.765 (0.439-1.333) 0.345 20 52.6% 0.975 (0.532-1.787) 0.935 0.627 (0.308-1.277) 0.198 Obese (≥25) Number of term-pregnancy Median, 2 (range, 0-8) 0.681 (0.545-0.850) 0.001 0.640 (0.508-0.806) <0.001 0.663 (0.522-0.841) 0.001 0.625 (0.474-0.824) 0.001 Abbreviations: BMI, body mass index; BRCT, BRCA1 C Terminus; CI, confidence interval; HR, hazard ratio; NAffected, number of affected carriers; NTotal, number of total carriers with BRCA1 mutations.
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Table 4. Breast and ovarian cancer risks related to risks factors among BRCA2 mutation carriers Breast cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
Ovarian cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
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Parameter NTotal NAffected % NAffected % Proportion of 112 77 68.8% 23 20.5% affected carrier Functional domains BRC repeats 12 5 41.7% 0.704 (0.301-1.647) 0.418 0.656 (0.275-1.568) 0.343 6 50.0% 3.283 (1.296-8.318) 0.012 3.129 (1.123-8.720) 0.029 DNA binding: 21 15 71.4% 1.501 (0.840-2.682) 0.170 1.110 (0.603-2.044) 0.738 3 14.3% 1.697 (0.476-6.051) 0.415 1.379 (0.358-5.310) 0.640 helical N/A N/A DNA binding: 3 3 100% 1.419 (0.441-4.568) 0.557 0.702 (0.162-3.049) 0.637 0 0% OB folds DNA binding: 0 0 0% N/A N/A 0 0% N/A N/A Tower Others 76 54 71.1% 1 1 14 18.4% 1 1 BMI (kg/m2) [n=107] Median, 22.2 (range, 16.6-32.9) Normal 57 38 66.7% 1 1 13 22.8% 1 1 (≥18.5 to <23) Underweight 5 5 100% 2.647 (0.965-6.306) 0.059 2.977 (0.903-9.819) 0.073 0 0% N/A N/A (<18.5) Overweight 14 8 57.1% 0.704 (0.327-1.516) 0.370 0.796 (0.358-1.770) 0.576 3 21.4% 0.417 (0.116-1.496) 0.180 0.350 (0.092-1.332) 0.124 (≥23 to <25) Obese 31 26 83.9% 0.925 (0.560-1.529) 0.762 1.112 (0.656-1.887) 1.112 8 25.8% 0.517 (0.209-1.277) 0.153 0.672 (0.250-1.811) 0.432 (≥25) Number of term-pregnancy Median, 2 (range, 0-8) 0.523 (0.411-0.666) <0.001 0.534 (0.419-0.681) <0.001 0.809 (0.508-1.288) 0.371 0.837 (0.519-1.349) 0.464 Abbreviations: BMI, body mass index; BRCT, BRCA1 C Terminus; CI, confidence interval; HR, hazard ratio; NAffected, number of affected carriers; NTotal, number of total carriers with BRCA2 mutations.
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(A)
(B) XUW
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mut
BRCA1
BRCA2mut WU_
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P = 0.164 YW
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WU]
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Cumulave incidence jG
WU_
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WU[
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vGGGO P Age at diagnosis of breast cancer (years)
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(A) BRCA1
frequency (n)
c.1471C>T (n=1) c.1480C>T (n=1)
1
frequency (n)
c.5030_5033delCTAA (n=2) c.5075-2A>G (n=1) c.5080G>T (n=5) c.5266dupC (n=1) c.5333-2A>T (n=1) c.5445G>A (n=3) c.5496_5506delGGTGACCCGAGinsA (n=8)
c.4253delT (n=1)
c.5511G>A (n=1)
5,589 nucleotides 1,863 AA
Coiled coil p.1253-1273 p.1397-1424
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(B) BRCA2
Serine-rich p.345-508
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RING p.24-64
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c.1511dupG (n=3)
c.3813dupT (n=1)
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c.1288C>T (n=1)
BRCT p.1643-1723 p.1756-1842
c.7480C>T (n=21)
c.5576_5579delTTAA (n=11) c.5590_5593delGACA (n=1)
c.3096_3110delAGATATT GAAGAACAinsT (n=1)
c.8002_8008dupAGAAGAT (n=1) c.9253delA (n=1) c.9254_925+11del (n=1)
10,254 nucleotides 1
3,418 AA BRC repeats p.1003-1035, 1213-1245, 1422-1454, 1518-1550, 1665-1696, 1838-1869, 1973-2004, 2052-2085
helical OB fold Tower OB fold p.2481 p.2670 p.2831 p.3052 -2667 -2796 - 2872 -3186
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Cumulave incidence
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BRCA1mut-L1780P BRCA1mut-BRCT
P = 0.012
BRCA1mut-ref
Age at diagnosis of breast cancer (years)
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S1526-8209(17)30785-1
DOI:
10.1016/j.clbc.2018.02.007
Reference:
CLBC 762
To appear in:
Clinical Breast Cancer
Received Date: 3 December 2017 Accepted Date: 10 February 2018
Please cite this article as: PARK JS, LEE S-T, HAN JW, KIM TI, NAM EJ, PARK HS, Difference in Risk of Breast and Ovarian Cancer According to Putative Functional Domain Regions in Korean BRCA1/2 Mutation Carriers, Clinical Breast Cancer (2018), doi: 10.1016/j.clbc.2018.02.007. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Type of Publication: Original Studies
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Title:
Difference in Risk of Breast and Ovarian Cancer According to Putative Functional Domain
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Regions in Korean BRCA1/2 Mutation Carriers
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Authors:
Ji Soo PARK, M.D.1 (E-mail: [email protected])
Seung-Tae LEE, M.D., Ph.D.1,2 (E-mail: [email protected])
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Jung Woo HAN, M.D.1,3 (E-mail: [email protected])
Tae Il KIM, M.D., Ph.D.1,4 (E-mail: [email protected])
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Eun Ji NAM, M.D., Ph.D.* 1,5 (E-mail: [email protected]) Hyung Seok PARK, M.D.* 1,6 (E-mail: [email protected]) These authors contributed equally to this work as corresponding authors.
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*
Affiliations: 1
Department of Hereditary Cancer Clinic, Cancer Prevention Center, Yonsei Cancer Center,
Yonsei University College of Medicine, Seoul, Korea
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Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea
3
Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
4
Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
5
Department of Obstetrics and Gynecology, Institute of Women’s Life Medical Science,
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2
Department of Surgery, Yonsei University College of Medicine, Seoul, Korea,
*Correspondence to: Prof. Eun Ji Nam, M.D., Ph.D.*
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6
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Women’s Cancer Clinic, Yonsei University College of Medicine, Seoul, Korea
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Department of Obstetrics and Gynecology, Institute of Women’s Life Medical Science, Women’s Cancer Clinic, Yonsei University College of Medicine, Seoul, Korea 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea
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Tel: 82-2-2228-2230 / Fax: 82-2-313-8357
and
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E-mail: [email protected]
Prof. Hyung Seok Park, M.D.*
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Department of Surgery
50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea Tel: 82-2-2228-2100 / Fax: 82-2-313-8289
These authors contributed equally to this work as corresponding authors.
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*
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E-mail: [email protected]; [email protected]
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Yonsei University College of Medicine
Total number of Text pages: 26
Figures: 3
Disclosure:
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Supplementary figure: 1
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Tables: 4
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The authors declare no conflict of interest.
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ABSTRACT PURPOSE:
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We investigated the relative risk of breast and ovarian cancers related to the putative functional domain regions, obesity, and parity among Korean BRCA1/2 mutation carriers.
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PATIENTS AND METHODS:
We analyzed the clinical characteristics, cancer history, and mutations according to the putative
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functional domain of BRCA proteins among 229 women with BRCA1/2 mutations who were treated at Yonsei Cancer Center, Severance Hospital between January 2009 and March 2017. RESULTS:
Twenty-two carriers (18.8% of 117 BRCA1 mutation carriers) with mutations located in the
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BRCT domain region had a higher risk of breast cancers (hazard ratio [HR], 2.851; 95% confidence interval [CI], 1.614-5.039; P < 0.001) than those with mutations outside of the putative functional domains of BRCA1. The risk of ovarian cancer was increased in 13 of 112
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BRCA2 mutation carriers (11.6%), with mutations located on BRC repeat regions (HR, 3.129; 95%, 1.123-8.720; P = 0.029). The term-pregnancies number was a significant risk-reducing
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factor for breast cancers in BRCA1 mutation carriers (HR per pregnancy, 0.640; 95%, 0.5080.806; P < 0.001), for breast cancers in BRCA2 mutation carriers (HR per pregnancy, 0.534; 95%, 0.419-0.681; P < 0.001), and for ovarian cancers for BRCA1 mutation carriers (HR per pregnancy, 0.625; 95%, 0.474-0.824; P = 0.001). CONCLUSION:
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Among Korean women with the BRCA1/2 mutation, the location of the mutations may influence the risk of breast and ovarian cancers according to the putative functional domain regions.
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Further investigations are required for risk prediction and preventive strategies in the BRCA1/2 mutation carriers.
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Key words:
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BRCA; putative functional domain; BRCT; BRC repeats; parity; risk of cancer
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INTRODUCTION Germline mutations in BRCA1 or BRCA2 confer an increased risk of breast and ovarian cancers.
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In previous reports, individuals with BRCA1 and BRCA2 mutations had lifetime risks of 60-72% and 45-69% for breast cancer, respectively, and lifetime risks of 39-59% and 11-17% for ovarian cancer, respectively 1-3. Because of the significantly higher risks of breast and ovarian cancers in
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individuals with BRCA1 and BRCA2 mutations compared with those of general population,
preventive strategies have been considered for selected carriers; for examples, risk-reducing
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salpingo-oophorectomy (RRSO), risk-reducing mastectomy (RRM), tamoxifen, and oral contraceptives 4-6. However, invasive interventions may induce substantial adverse events, including sexual dissatisfaction, cardiovascular diseases, osteoporosis, postmenopausal symptoms followed by premature menopause, and psychological, financial, and/or cosmetic
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problems from RRM 7,8. Therefore, personalized cancer risk prediction was introduced for BRCA1/2 mutation carriers 9,10. This approach helps reduce the adverse event of invasive management and improves the effect of preventive strategies.
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Meanwhile, BRCA1 and BRCA2 proteins have several functional domains that bind to their unique binding partners. Some examples of highly active and conserved regions of BRCA1
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protein include the RING domain, which interacts with the BRCA1-associated RING domain protein 1 (BARD1); the BRCA1 C Terminus (BRCT) domain, which functions with its partner proteins abraxas, CtBP-interacting protein (CtIP), and BRCA1-interacting protein C-terminal helicase 1 (BRIP1); and coiled-coil domain, which binds to BRCA2 via PALB2 11. The BRCA2 proteins have DNA-binding domains (DBDs), which contain a helical domain, oligonucleotide binding (OB) folds, a tower domain, and eight BRC repeats combined with RAD51 11. In a
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recent large clinical study, the Consortium of Investigators of Modifiers of BRCA (CIMBA) reported the relative cancer risk of women with the BRCA1/2 mutation within the putative breast
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cancer cluster regions (BCCRs), ovarian cancer cluster regions (OCCRs), and functional domains 12. Among the carriers of BRCA1/2 mutations, breast and ovarian cancer risks were different according to the location of the specific mutations 12,13. In addition, non-genetic risk
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factors, including reproductive factors and body weight, were reported to possibly influence the occurrence of breast cancer 14,15. These findings can be used for risk prediction and cancer
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prevention of the carriers.
In this study, we evaluated the relative risks of breast cancer and ovarian cancer according to putative functional domain regions and clinical risk factors among Korean women with BRCA1/2
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germline mutations.
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MATERIAL AND METHODS Study population
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Between January 2009 and March 2017, 1,510 Korean women carrying at least one clinical feature of suspicious hereditary breast-ovarian cancer syndrome (HBOC) were evaluated for BRCA1 and BRCA2 germline mutation status in Yonsei Cancer Center, Severance Hospital,
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Seoul, Republic of Korea. The risk factors included the following: 1) a breast cancer patient with at least one first- or second-degree relative with breast and/or ovarian cancer; 2) a patient with
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breast cancer diagnosed before age 40; 3) a patient with bilateral breast cancer; 4) a breast cancer patient with other multiple primary cancers; 5) a patient with epithelial ovarian cancer; 6) a male breast cancer patient; and 7) a member of a family of known BRCA1/2 mutation carriers. Patients who met the following eligibility criteria were included in this study: 1) those who were
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known to be BRCA1/2 germline mutation carriers as proven by accepted methods; 2) those who were ≥19 years of age; and 3) those who were women. To analyze the breast and ovarian cancer risks according to locations of the mutations and reproductive factors, we defined the exclusion
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criteria as follows: 1) male mutation carriers; 2) patients with BRCA1/2 large intragenic
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rearrangement including deletions, duplication, or insertion of the exons; and 3) patients who already underwent bilateral salpingo-oophorectomy before the test of BRCA1/2 mutations, due to reasons other than ovarian cancer. We retrospectively reviewed the results of the medical records of the patients regarding BRCA1/2 germline mutation tests, clinicopathological features of breast and ovarian cancers, body mass index (BMI, kg/m2) at first visit to the clinic, parity, and termpregnancy number.
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We followed the medical research protocols and ethics guidelines defined by the World Medical Association’s Declaration of Helsinki throughout the study. The protocol was reviewed and
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approved by the local Institutional Review Board (IRB approval number: 4-2017-0521).
BRCA1 and BRCA2 genes analyses
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After extraction of genomic DNA from peripheral blood of the patients, the entire coding region
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(exon 2-23) and intron-exon boundaries (28 base pairs) of BRCA1 on chromosome 17q21 and the entire coding region (exon 2-27) and intron-exon boundaries (20 base pairs) of BRCA2 on chromosome 13q12.3 were amplified using polymerase chain reaction (PCR) amplification. The amplified products were directly sequenced using fluorescent dye-labeled sequencing primers. Genetic variants were analyzed by comparison with a consensus wild-type sequence of each
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gene (NM_007294.3 for BRCA1 and NM_000059.3 for BRCA2). We classified the deleterious genetic variants by introducing premature termination codons through frameshift, nonsense, and splice junction alterations as pathogenic variants, which were referred to as ‘mutations’ in this
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study. Most variant of unknown significance (VUS) included missense mutation, small in-frame
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deletions and insertions, synonymous substitution, alteration in non-coding intervening sequences (IVS), or untranslated exonic regions (UTRs).
Nomenclature system of variants
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We followed the Human Genome Organisation (HUGO)-approved nomenclature system of the Human Genome Variation Society (http://www.hgvs.org/mutnomen) for description of the
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variants.
Putative functional domain regions
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We defined the risk group in this study as the carriers with pathogenic variants located on the
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following putative functional domains: RING, coiled-coil, and BRCT domains of BRCA1; and BRC repeats, helical, OB-folds, and tower domains of BRCA2. The locations of putative functional domains were defined using the boundaries in the Pfam database 16. We used the carriers with mutations outside of the putative functional domains as a reference group to
Definitions
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estimate the relative risks of breast and ovarian cancers of the risk group.
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To estimate the influence of obesity on the risk of breast/ovarian cancers in BRCA1/2 mutation carriers, we collected the BMIs of the patients at each patient’s first visit to our clinic, and
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divided the BMIs into the following four categories according to the World Health Organization (WHO) definition of obesity and overweight for the Asian population: underweight, <18.5 kg/m2; normal, ≥18.5 kg/m2 and <23 kg/m2; overweight, ≥23 kg/m2 and <25 kg/m2; obese, ≥25 kg/m2 17. Parity indicates the number of pregnancies reaching viable gestational age, including viable births and stillbirths, and term-pregnancy was defined as ‘a pregnancy resulting in a delivery that occurs between 37 weeks 0 days and 41 weeks 6 days’ 18.
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Statistical analyses
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The cumulative incidences of breast/ovarian cancers in BRCA1/2 mutation carriers were
analyzed using the Kaplan-Meier method, and survival curves were compared using log-rank tests. We used Pearson’s χ2 tests, Mann-Whitney U tests, and linear regression analyses to
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evaluate the clinicopathological differences between the carriers with BRCA1 and BRCA2
mutations. The relative risks of breast cancer and ovarian cancers in the carriers with a BRCA1/2
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mutation in putative functional domains were estimated using Cox’s proportional hazard regression model. In the Cox regression model, BMI and reproductive factors were also used, with the putative functional domain regions as covariates. A P-value of <0.05 was considered statistically significant. All statistical analyses were performed using SPSS 23 for Windows
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(IBM, Armonk, NY, USA)
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RESULTS Patient characteristics
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Among the 1,510 Korean women with BRCA1/2 germline mutation who were evaluated, 250 subjects (16.6%; 128 subjects with BRCA1 mutations and 122 subjects with BRCA2 mutations) had one of 97 kinds of deleterious mutations, and the other 255 patients (16.9%) had VUS only.
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Of the 250 BRCA1/2 mutation carriers, we excluded 12 men, five carriers with large
rearrangement of exons in BRCA1/2 genes (all patients had large exonic deletions), and four
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carriers who had already received bilateral salpingo-oophorectomy due to reasons other than ovarian cancer. Finally, 117 cases with BRCA1 mutations and 112 cases with BRCA2 mutations
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were included in this analysis (Fig S1).
Clinicopathological features of BRCA1/2 mutation carriers There were 116 patients with breast cancer, 53 patients with ovarian cancer, 31 patients with
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both breast and ovarian cancers, and 29 unaffected carriers. All the carriers were followed up until the median age of the group (50.8 years; range, 21.1-84.1 years), and no one received
tests.
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prophylactic mastectomy or salpingo-oophorectomy before they underwent BRCA1/2 genetic
Among 147 patients who had been diagnosed with breast cancer, there was no difference between the patients with BRCA1 and BRCA2 mutations in the ages at diagnosis of first breast cancer, literalities, and histological features. Subtypes of breast cancers varied between BRCA1 and BRCA2 carriers; specifically, BRCA1 mutation carriers had more triple negative breast
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cancers (TNBCs; 71.6%), and BRCA2 mutation carriers had more estrogen receptor (ER)positive breast cancer (62.4%). Among the 84 patients with ovarian cancers, there were no
between BRCA1 and BRCA2 mutation carriers (Table 1).
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differences in the ages at diagnosis of ovarian cancers and histologic features of ovarian cancers
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Cumulative incidence of breast cancer and ovarian cancer in BRCA1/2 mutation carriers
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Among the 117 BRCA1 mutation carriers, 70 (59.8%) were diagnosed with breast cancer at the median age of 49.9 years (95% confidence interval [CI], 43.9-55.9) Among the 112 BRCA2 mutation carriers, 77 (68.8%) were diagnosed with breast cancer at the median age of 46.8 years (95% CI, 44.0–49.6). The hazard ratio (HR) of cumulative incidence in BRCA1 mutation carriers
0.164) (Fig 1A).
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[BRCA1mut] versus BRCA2 mutation carriers [BRCA2mut] was 0.794 (95% CI = 0.573–1.100; P =
In addition, 60 of 117 (51.3%) BRCA1 mutation carriers were diagnosed with ovarian cancer at
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the median age of 56.5 years (95% CI, 53.3–59.7). The cumulative risk of ovarian cancers in the carriers with BRCA1 mutations was significantly higher than that in the carriers with BRCA2
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mutations (24 of 112 carriers [21.4%]; median age, 60.7 years; 95% CI, 58.5–63.0; HR of cumulative incidence in BRCA1mut versus BRCA2mut, 2.252; 95% CI, 1.400–3.624; P = 0.001) (Fig 1B).
Frequency of the mutations located at putative functional domain regions in BRCA1/2
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Among 117 carriers with BRCA1 mutations, we found six (5.1%) mutations located on the serine-rich domain, two (1.7%) mutations on the coiled-coil domain, and 22 (18.8%) mutations
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on the BRCT domain. Among 112 carriers with BRCA2 mutations, there were 13 (11.6%) mutations on BRC repeats, 21 (18.8%) mutations on the helical domain, and three (2.7%)
mutations on the OB-fold domain. No mutations were found on the RING domain of BRCA1
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and the tower domain of BRCA2 (Table 2 and Fig 2).
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Relative risk related to the occurrence of breast and ovarian cancers in BRCA1/2 mutation carriers according to putative functional domains, obesity, and term-pregnancy number Among the carriers with BRCA1 mutations, deleterious mutations resulting in changes of amino acids located on the BRCT domain [BRCA1mut-BRCT] were correlated with a higher risk of breast
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cancers than mutations outside of the putative functional domain regions [BRCA1mut-ref] (p.1643– 1723 and p.1756–1842; HR, 2.851; 95% CI, 1.614–5.039; P < 0.001). In addition, the risk of breast cancer was reduced with the increase in term-pregnancy number (HR per each pregnancy,
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0.640; 95%, 0.508–0.806; P < 0.001) (Table 3). Among the carriers with BRCA2 mutations, the
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risk of ovarian cancer was correlated with BRC repeats of BRCA2 (p.1003–1035, p.1213–1245, p.1422–1454, p.1518–1550, p.1665–1696, p.1838–1869, p.1973–2004, and p.2052–2084; HR versus mutations outside of putative functional domain regions [BRCA2mut-ref], 3.129; 95% CI, 1.123–8.720; P = 0.029) (Table 4). In addition, the term-pregnancy number was a significant risk-reducing factor for breast cancers in BRCA2 mutations carriers (HR per each pregnancy, 0.534; 95% CI, 0.419–0.681; P < 0.001)
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(Table 4) and ovarian cancers in BRCA1 mutations carriers (HR per each pregnancy, 0.625;
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95%CI, 0.474–0.824; P = 0.001) (Table 3).
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DISCUSSION In the present study, we analyzed risk factors (putative functional domain regions, obesity, and
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term-pregnancy number) related to cumulative incidences of breast and ovarian cancer among Korean women with BRCA1/2 germline mutations. We found that BRCT domain regions were associated with increased risk of breast cancers among BRCA1 mutation carriers, and BRC
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repeats regions were associated with increased risk of ovarian cancers among BRCA2 mutation carriers. Furthermore, the term-pregnancy number was related to decreased risk of breast cancer
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among BRCA1/2 mutation carriers and ovarian cancer among BRCA1 mutation carriers. The pathological characteristics of the carriers with BRCA1/2 mutations were consistent with previous reports 19. However, because most of the participants (88.3%) of this study were affected carriers, the cumulative risks of breast and ovarian cancers may be overestimated
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(cumulative risks of breast cancer up to age 70 years were 83% among BRCA1 mutation carriers and 86% among BRCA2 mutation carriers; cumulative risks of ovarian cancer up to age 70 years were 89% among BRCA1 mutation carriers and 66% among BRCA2 mutation carriers) compared
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to those in a recent clinical study of a large population including affected and unaffected carriers (67% and 66% cumulative risk of breast cancer and 45% and 12% cumulative risk of ovarian
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cancer in BRCA1 and BRCA2 mutation carriers aged 80 years, respectively) 20. The discordance of these studies may be mainly due to different study populations, which needs to be considered when interpreting the results. The cumulative risks of breast and ovarian cancers of the study may be primarily influenced by the affected carriers, with potential risk factors like putative functional domain regions, obesity, and term-pregnancy number, and not by the unaffected carriers.
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Rebbeck et al. suggested that the risk of breast cancer was significantly higher in the carriers with mutations in the BRCT domains and lower in the carriers with mutations in BRC repeats.
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They also reported co-locations between BRCT domains and putative BCCR2’ (c.5261–5563), and between BRC repeats and putative OCCR1 (c.3249–5681, and c.5946) 12. Kuchenbaecker et al. reported that age-specific risks of breast cancer were increased in the carriers with mutations
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outside c.2282–4071 in BRCA1 and c.2831–6401 in BRCA2 13. Our results were consistent these previous reports. In addition, the risk of ovarian cancer was significantly increased in the carriers
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with the mutations at BRC repeats regions in BRCA2. The BRC repeats in BRCA2 are known to bind to RAD51, which is an essential recombinase enzyme for repair DSB in DNA by homologous recombination 21,22. Therefore, BRCA2 with mutations at BRC repeats were possibly defective in recruiting RAD51 to the sites of DSB and, as a result, may affect cancer susceptibility 21. Moreover, there is clinical evidence that the carriers with deleterious mutations
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in RAD51C and RAD51D had significantly increased risks of ovarian cancers 23. Further clinical research and functional studies will help clarify the cancer risk and the its mechanisms by
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mutations of BRC repeats at BRCA2 protein.
In a previous study, we found that the missense variant of BRCA1 c.5339T>C (p.Leu1780Pro;
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rs80357474) is a pathogenic mutation in Korean patients according to American College of Medical Genetics and Genomics (ACMG) standards and guidelines for interpreting sequence variants 24. Because BRCA1 Leu1780 was located at the C-terminal end of the BRCT domain, the replacement of leucine with proline and following changes in structures had been predicted to cause a higher risk of disease 25. In comparison with the carriers with other known deleterious mutations located at BRCT domains or BRCA1mut-ref, the relative risk of breast cancer among the carriers of BRCA1 Leu1780Pro have not been estimated. Among 1,510 patients in this study, we
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found 13 patients with BRCA1 Leu1780Pro, who were not included in the 250 patients with known deleterious mutations. Among the 13 carriers with BRCA1 Leu1780Pro, 11 carriers were
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diagnosed with breast cancers at the median age of 38.4 years (95% CI, 33.9–42.9). By comparison, 18 of 22 patients with BRCA1 mutations located at BRCT domains were diagnosed with breast cancers at a median age of 39.0 years (95% CI, 35.1–42.9) years of age. The age at
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diagnosis of breast cancer was not significantly different between patients with Leu1780Pro and those with known deleterious mutations located on BRCT domain (P = 0.885). However, age at
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diagnosis of breast cancer in patients with mutations at BRCT domain was significantly earlier than those with BRCA1mut-ref (median, 51.0; 95% CI, 45.0–57.0; P = 0.012) (Fig 3). This result indicates that BRCA1 mutations located at BRCT domain regions were associated with early onset of breast cancer. In addition, onset of breast cancer among the carriers with BRCA1
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Leu1780Pro is similar to those of the carriers with BRCA1 mutations located at BRCT domains. Because hormonal exposure is significantly correlated with occurrence of breast cancer in women, several reproductive factors (e.g., early menarche, late menopause, nulliparity, and no
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breastfeeding) have been studied as potential strong risk factors for women to develop breast cancer. A previously published meta-analysis showed that multiparity with more than three live
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births is associated with reduced risk of breast cancer in BRCA1/2 mutation carriers, and multiparity with more than four live births is related to decreased risk of ovarian cancer in BRCA1 mutation carriers 26. In this study, parous (with any live birth) women had significantly lower risks of breast cancer than nulliparous women among BRCA1 mutations carriers (HR, 0.367; 95% CI, 0.207–0.650; P = 0.001), and among BRCA2 mutation carriers (HR, 0.233; 95% CI, 0.134–0.404; P<0.001), and lower risk of ovarian cancers among BRCA1 mutation carriers (HR, 0.368; 95% CI, 0.172–0.786; P = 0.010). We also found a significant increase trend in the
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term-pregnancy number, and a reduced risk of development of breast and ovarian cancers. These factors related to estrogen exposure, including hormone replacement therapy, parity, and number
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of child-bearing pregnancies, are partially modifiable in the carriers. Therefore, future research and adequate application to clinics are required for preventive strategies to treat carriers with BRCA1/2 mutations.
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Obesity is another well-known risk factor of breast cancer. However, the results of this study did not show a significant correlation between obesity and the risk of breast cancer. This result is
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possibly due to the different standards of obesity in the Asian population and the relatively higher proportion of premenopausal women with breast cancer among Korean BRCA1/2 mutation carriers. A WHO expert consultation addressed the issue that a stricter BMI was recommended for Asian populations compared with European populations. Because Asian
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people have a high risk of type 2 diabetes mellitus and cardiovascular diseases at BMIs lower than the WHO cut-off point for being overweight (≥ 25 kg/m2), BMI cut-off points should be redefined for Asian population separately 17. Interestingly, the epidemiologic studies showed that
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BMI of ≥ 25 kg/m2 is not associated with excess risk of death from any cause of death in the Asian population. Rather, being underweight is related to increased risk of death in all Asian
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populations 27, and Korean patients with a BMI of 23.0–24.9 kg/m2 have the lowest risk of death from any cause 28. Thus, there is a need to establish new standards for overweight and obesity in Korean populations. The strict standard of normal BMI (≥18.5 to <23 kg/m2), resulting in classification of more women as overweight or obese, possibly influenced the analysis of the relationship between breast cancer risk and obesity in Korean BRCA1/2 mutation carriers. Another reason that obesity did not influence the relative risk of breast cancer in Korean populations is that obesity has a strong association with estrogen receptor-positive breast cancers
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in postmenopausal women 29. In contrast, breast cancers with BRCA1/2 mutations occur in young, premenopausal women 30,31, and most breast cancers present as estrogen receptor-negative types
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among BRCA1 mutation carriers 19,31. In addition, body weight is not static but can change by one’s lifestyle. A reference point of obesity in an individual life and long-term follow-up is needed for accurate analyses.
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There are several limitations to this study. Because of the small number of carriers, cancer risks related to several putative functional domain regions could be underestimated. Other known risk
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factors, including reproductive factors (age at menarche, breast feeding, oral contraceptive, and hormone replacement therapy), physical activity, alcohol consumption, smoking, and early radiation exposure were not evaluated due to lack of data in the medical records. Despite these limitations, to the best of our knowledge, this is the first study analyzing the risk of
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breast and ovarian cancer according to putative functional domain regions in Korean BRCA1/2 mutation carriers, with adjustment for other well-known risk factors like obesity and termpregnancy number. We will analyze the relative cancer risks according to functional domains in
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multi-center large clinical database in Korea.
CONCLUSION
We suggest that mutations according to putative functional domains of BRCA proteins may influence risk and onset time of breast and ovarian cancers in BRCA1/2 mutation carriers. Understanding the landscape regarding mutations in functional domain regions may provide meaningful insights into cancer risks and preventive strategies among Korean women with BRCA1/2 mutations.
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SHORT CLINICL PRACTICE POINT Germline mutations in BRCA1 or BRCA2 confer an increased risk of breast and ovarian
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cancers. Although clinical guidelines recommend preventive strategies including riskreducing salpingo-oophorectomy (RRSO), risk-reducing mastectomy (RRM), tamoxifen, and oral contraceptives, invasive interventions may induce substantial adverse events.
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In this study, we suggested that the locations of BRCA1/2 mutation affected the risk of breast and ovarian cancers. Higher cancer risk was related to BRCT domain of BRCA1
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for breast cancer, and BRC repeats of BRCA2 for ovarian cancer.
We also found that parity was a risk-reducing factor for breast cancer among BRCA1/2 mutation carriers, and for ovarian cancer among BRCA1 mutation carriers.
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These risk factors will be applied to predict occurrence and cumulative risk of cancer of each carrier. Personalized prediction of breast and ovarian cancer risks will be used to reduce adverse events of invasive management and improve the efficacy of preventive
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strategies for BRCA1/2 mutation carriers.
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Acknowledgements
The results of this study were presented as part of the 24th Asia Pacific Cancer Conference (APCC) held on June 22nd–24th, 2017, Seoul, Republic of Korea. The authors thank Bio Science Writers (http://www.biosciencewriters.com/) for English language editing service.
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Funding This research did not receive any specific grant from funding agencies in the public, commercial,
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or not-for-profit sectors.
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Figure legends
Fig 1. Differences in cumulative incidence of breast and ovarian cancer between BRCA1 and
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BRCA2 mutation carriers: (A) breast cancer; (B) ovarian cancer.
Fig 2. Locations with frequency of the mutations according to putative function domains: (A) BRCA1; (B) BRCA2.
Fig 3. Cumulative incidences of breast cancers among the carriers with BRCA1 mutations
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located at BRCT domain, L1780P, and outside of putative functional domain.
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Table 1. Baseline characteristics
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41.9 (22.6-71.8)
41.6 (22.2-81.0)
0.278*
61 16
79.2% 20.8%
113 34
76.9% 23.1%
0.479
58 5 1 17 12
62.4% 5.4% 1.1% 18.3% 12.9%
71 5 1 80 24
39.2% 2.8% 0.6% 44.2% 13.3%
<0.001†
74 6 1 1 6 5
79.6% 6.5% 1.1% 1.1% 6.5% 5.4%
149 7 2 1 11 11
82.3% 3.9% 1.1% 0.6% 6.1% 6.1%
0.435†
P-value <0.001
55.2 (46.5-71.7)
53.7 (28.7-78.7)
0.120*
19 1 0 1 1 1
69 1 2 3 1 8
0.109†
82.8% 4.3% 0% 4.3% 4.3% 4.3%
M AN U
Breast cancer Ovarian cancer Breast and ovarian cancer Unaffected carrier Breast cancer (N=147) Age at diagnosis [years, median] (range) 40.8 (22.2-81.0) Laterality Unilateral 52 74.3% Bilateral 18 25.7% Subtype (total of first and secondary breast cancers, N=181) ER+ 13 14.8% ER+/HER2+ 0 0% HER2+ 0 0% TNBC 63 71.6% unknown 12 13.6% Histology (total of first and secondary breast cancers, N=181) IDC 75 85.2% DCIS 1 1.1% ILC 1 1.1% LCIS 0 0% others 5 5.8% unknown 6 6.8% Ovarian cancer (n=84) Age at diagnosis [years, median] (range) 52.9 (28.7-78.7) Histology Serous carcinoma 49 81.7% Mucinous carcinoma 0 0% Endometrioid carcinoma 2 3.3% Poorly differentiated 2 3.3% others 0 0% unknown 7 11.7%
Total (N=229) Number % 116 50.7% 53 23.1% 31 13.5% 29 12.7%
RI PT
Type of cancer
BRCA2 mutation carriers (N=112) Number % 69 61.6% 16 14.3% 8 7.1% 19 17.0%
SC
BRCA1 mutation carriers (N=117) Number % 47 40.2% 37 31.6% 23 19.7% 10 8.5%
82.1% 1.2% 2.4% 3.6% 1.2% 9.5%
Abbreviations: DCIS, ductal carcinoma in situ; ER, estrogen receptor; HER2, human epidermal growth factor 2; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; LCIS, lobular carcinoma in situ; N, number; TNBC, triple negative breast cancer. Key: (*) analyzed using the
AC C
EP
TE D
Mann-Whitney U test; (†) analyzed using the Fisher’s exact test.
Table 2. Frequency of mutations according to the putative functional domain of BRCA1 and BRCA2
ACCEPTED MANUSCRIPT
Coiled Coil
2
1.7%
BRCT
22
18.8%
87
74.4%
Effect on amino acids
Type
c.1288C>T c.1471C>T c.1480C>T c.1511dupG c.3813dupT c.4253delT c.5030_5033delCTAA c.5075-2A>G c.5080G>T c.5266dupC c.5333-2A>T c.5445G>A c.5496_5506delGGTGACCCGAGinsA c.5511G>A c.213-1G>A c.302-2A>C c.302-1G>C c.390C>A c.928C>T c.922_924delAGCinsT c.1016dupA c.1630C>T c.1716delA c.1729G>T c.1823delA c.1831delC c.2048delA c.2345delG c.2354T>A c.2433delC c.3228_3229delAG c.3277delG c.3296delC c.3340G>T c.3442delG c.3627dupA c.3895C>T c.3954dupT c.4041_4042delAG c.4092_4093delCT c.4120_4121delAG c.4127_4128delCA c.4286_4290delACCCT c.4327C>T c.4335_4338dupAGAA c.4485-2A>G c.5194-2A>G c.5260G>T
p.Gln430Ter p.Gln491Ter p.Gln494Ter p.Lys505Terfs p.Asn1272Terfs p.Leu1418Ter p.Thr1677Ilefs
p.Glu1754Ter
NS NS NS FS FS NS FS S NS FS S NS FS NS S S S NS NS FS FS NS FS NS FS FS FS FS NS FS FS FS FS NS FS FS NS FS FS FS FS FS FS NS FS S S NS
n 0 1 1 1 3 1 1 2 1 5 1 1 3 8 1 1 1 2 14 1 9 3 1 1 1 1 1 1 3 3 2 1 1 2 4 5 14 2 1 1 2 2 1 1 1 1 1 1 1
Genetic variant (DNA level) c.3096_3110delAGATATTGAAGAACAinsT c.5576_5579delTTAA c.5590_5593delGACA c.7480C>T
Effect on amino acids p.Lys1032Asnfs p.Ile1859Lysfs p.Asp1864Tyrfs p.Arg2494Ter
Type FS FS FS NS
n 1 11 1 21
p.Glu1694Ter p.Gln1756Profs
p.Trp1815Ter p.Val1833Serfs p.Trp1837Ter
p.Tyr130Ter p.Gln310Ter p.Ser308Terfs p.Val340Glyfs p.Gln544Ter p.Glu572Aspfs p.Glu577Ter p.Lys608Argfs p.Leu611Terfs p.Lys683Serfs p.Ser782Ilefs p.Leu785Ter p.Lys812Argfs p.Gly1077Alafs p.Val1093Serfs p.Pro1099Leufs p.Glu1114Ter p.Glu1148Argfs p.Glu1210Argfs p.Gln1299Ter p.Gly1319Trpfs p.Gly1348Asnfs p.Leu1365Argfs p.Ser1374Terfs p.Thr1376Lysfs p.Tyr1429Phefs p.Arg1443Ter p.Gln1447Argfs
AC C
EP
TE D
M AN U
SC
Other
Genetic variant (DNA level)
RI PT
BRCA1 functional domains (n=117) Domain n (domain) % RING 0 0% Serine-rich 6 5.1%
BRCA2 functional domains (n=112) Domain n (domain) % BRC repeats 13 11.6%
DNA binding: helical DNA binding: OB folds DNA binding: Tower Others
21
18.8%
3
2.7%
c.8002_8008dupAGAAGAT c.9253delA c.9254_9256+11del
p.Ser2670Terfs p.Thr3085Glnfs
FS FS S
1 1 1 0
66.9%
c.276dupA c.370delA c.475+1G>T c.516+1G>A c.632-1G>T c.755_758delACAG c.800delG c.994delA
p.Ser93Ilefs p.Met124Trpfs
FS FS S S S FS FS FS
1 2 1 1 1 2 2 2
0 75
p.Asp252Valfs p.Gly267Glufs p.Ile332Phefs
AC C
EP
TE D
M AN U
SC
RI PT
c.1309_1312delAAAG p.Lys437Ilefs c.1399A>T p.Lys467Ter ACCEPTED MANUSCRIPT c.1495C>T p.Gln499Ter c.1794_1798delATCTT p.Ser599Terfs c.2130_2131insAA p.Cys711Asnfs c.2376C>A p.Tyr792Ter c.2588dupA p.Asn863Lysfs c.2683_2684dupGC p.Asn896Leufs c.2786T>G p.Leu929Ter c.2798_2799delCA p.Thr933Argfs c.2808_2811delACAA p.Ala938Profs c.3170_3174delAGAAA p.Lys1057Thrfs c.3744_3747delTGAG p.Ser1248Argfs c.3837delT p.Asn1279Lysfs c.4372delC p.His1458Ilefs c.4471_4474delCTGA p.Leu1491Lysfs c.5699C>G p.Ser1900Ter c.6428C>A p.Ser2143Ter c.6437_6440delATCA p.Asn2146Thrfs c.6600_6601delTT p.Ser2201Terfs c.6952C>T p.Arg2318Ter c.7368_7371delGTTT p.Phe2457Thrfs c.7375A>T p.Lys2459Ter c.8488-1G>A c.8991T>G p.Tyr2997Ter c.9018C>A p.Tyr3006Ter c.9076C>T p.Gln3026Ter c.9105T>G p.Tyr3035Ter Abbreviations: BRCT, BRCA1 C Terminus; FS, frameshift; NS, nonsense; S, splicing; OB, oligonucleotide binding.
FS NS NS FS FS NS FS FS NS FS FS FS FS FS FS FS NS NS FS FS NS FS NS S NS NS NS NS
2 14 1 2 2 2 1 2 1 4 5 1 4 2 1 2 1 1 1 1 1 2 1 1 1 1 5 1
ACCEPTED MANUSCRIPT
Table 3. Breast and ovarian cancer risks related to risks factors among BRCA1 mutation carriers Parameter
Breast cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
Ovarian cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
AC C
EP
TE D
M AN U
SC
RI PT
NTotal NAffected % NAffected % Proportion of 117 70 59.8% 59 50.4% affected carrier Functional domains RING 0 0 0 N/A N/A 0 0 N/A N/A Serine-rich 6 1 16.7% 0.453 (0.062-3.285) 0.433 0.421 (0.056-3.146) 0.399 3 50.0% 3.015 (0.913-9.963) 0.070 3.210 (0.901-11.43) 0.072 2 100% 0.609 (0.146-2.546) 0.497 0.949 (0.122-7.361) 0.960 Coiled Coil 2 1 50% 0.605 (0.083-4.319) 0.619 N/A BRCT 22 18 81.8% 1.865 (1.080-3.222) 0.025 2.851 (1.614-5.039) <0.001 10 45.5% 0.692 (0.345-1.390) 0.301 1.171 (0.570-2.407) 0.667 Other 87 50 57.5% 1 1 44 50.6% 1 1 BMI (kg/m2) [n=114] Median, 22.8 (range, 15.7-39.4) Normal 54 34 63.0% 1 1 24 44.4% 1 1 (≥18.5 to <23) Underweight 5 3 60.0% 1.205 (0.368-3.945) 0.758 1.300 (0.391-4.324) 0.669 3 60.0% 1.930 (0.572-6.514) 0.289 1.065 (0.302-3.750) 0.922 (<18.5) Overweight 17 10 58.8% 0.534 (0.262-1.088) 0.084 0.577 (0.278-1.196) 0.139 11 64.7% 0.523 (0.253-1.078) 0.079 0.505 (0.238-1.070) 0.075 (≥23 to <25) 38 22 57.9% 0.805 (0.469-1.382) 0.431 0.765 (0.439-1.333) 0.345 20 52.6% 0.975 (0.532-1.787) 0.935 0.627 (0.308-1.277) 0.198 Obese (≥25) Number of term-pregnancy Median, 2 (range, 0-8) 0.681 (0.545-0.850) 0.001 0.640 (0.508-0.806) <0.001 0.663 (0.522-0.841) 0.001 0.625 (0.474-0.824) 0.001 Abbreviations: BMI, body mass index; BRCT, BRCA1 C Terminus; CI, confidence interval; HR, hazard ratio; NAffected, number of affected carriers; NTotal, number of total carriers with BRCA1 mutations.
ACCEPTED MANUSCRIPT
Table 4. Breast and ovarian cancer risks related to risks factors among BRCA2 mutation carriers Breast cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
Ovarian cancer Simple regression Multiple regression HR (95% CI) P HR (95% CI) P
AC C
EP
TE D
M AN U
SC
RI PT
Parameter NTotal NAffected % NAffected % Proportion of 112 77 68.8% 23 20.5% affected carrier Functional domains BRC repeats 12 5 41.7% 0.704 (0.301-1.647) 0.418 0.656 (0.275-1.568) 0.343 6 50.0% 3.283 (1.296-8.318) 0.012 3.129 (1.123-8.720) 0.029 DNA binding: 21 15 71.4% 1.501 (0.840-2.682) 0.170 1.110 (0.603-2.044) 0.738 3 14.3% 1.697 (0.476-6.051) 0.415 1.379 (0.358-5.310) 0.640 helical N/A N/A DNA binding: 3 3 100% 1.419 (0.441-4.568) 0.557 0.702 (0.162-3.049) 0.637 0 0% OB folds DNA binding: 0 0 0% N/A N/A 0 0% N/A N/A Tower Others 76 54 71.1% 1 1 14 18.4% 1 1 BMI (kg/m2) [n=107] Median, 22.2 (range, 16.6-32.9) Normal 57 38 66.7% 1 1 13 22.8% 1 1 (≥18.5 to <23) Underweight 5 5 100% 2.647 (0.965-6.306) 0.059 2.977 (0.903-9.819) 0.073 0 0% N/A N/A (<18.5) Overweight 14 8 57.1% 0.704 (0.327-1.516) 0.370 0.796 (0.358-1.770) 0.576 3 21.4% 0.417 (0.116-1.496) 0.180 0.350 (0.092-1.332) 0.124 (≥23 to <25) Obese 31 26 83.9% 0.925 (0.560-1.529) 0.762 1.112 (0.656-1.887) 1.112 8 25.8% 0.517 (0.209-1.277) 0.153 0.672 (0.250-1.811) 0.432 (≥25) Number of term-pregnancy Median, 2 (range, 0-8) 0.523 (0.411-0.666) <0.001 0.534 (0.419-0.681) <0.001 0.809 (0.508-1.288) 0.371 0.837 (0.519-1.349) 0.464 Abbreviations: BMI, body mass index; BRCT, BRCA1 C Terminus; CI, confidence interval; HR, hazard ratio; NAffected, number of affected carriers; NTotal, number of total carriers with BRCA2 mutations.
ACCEPTED MANUSCRIPT
(A)
(B) XUW
XUW
mut
BRCA1
BRCA2mut WU_
WU[
WUY
WUW W
XW
TE D
P = 0.164 YW
ZW
[W
jG Cumulave incidence
RI PT SC
WU]
M AN U
Cumulave incidence jG
WU_
WU]
WU[
WUY
P< WUW
\W
]W
^W
_W
`W
XWWUW
AC C
EP
vGGGO P Age at diagnosis of breast cancer (years)
㯱GX
㯱GX
W
X
SC
RI PT
ACCEPTED MANUSCRIPT
(A) BRCA1
frequency (n)
c.1471C>T (n=1) c.1480C>T (n=1)
1
frequency (n)
c.5030_5033delCTAA (n=2) c.5075-2A>G (n=1) c.5080G>T (n=5) c.5266dupC (n=1) c.5333-2A>T (n=1) c.5445G>A (n=3) c.5496_5506delGGTGACCCGAGinsA (n=8)
c.4253delT (n=1)
c.5511G>A (n=1)
5,589 nucleotides 1,863 AA
Coiled coil p.1253-1273 p.1397-1424
EP
(B) BRCA2
Serine-rich p.345-508
AC C
RING p.24-64
TE D
c.1511dupG (n=3)
c.3813dupT (n=1)
M AN U
c.1288C>T (n=1)
BRCT p.1643-1723 p.1756-1842
c.7480C>T (n=21)
c.5576_5579delTTAA (n=11) c.5590_5593delGACA (n=1)
c.3096_3110delAGATATT GAAGAACAinsT (n=1)
c.8002_8008dupAGAAGAT (n=1) c.9253delA (n=1) c.9254_925+11del (n=1)
10,254 nucleotides 1
3,418 AA BRC repeats p.1003-1035, 1213-1245, 1422-1454, 1518-1550, 1665-1696, 1838-1869, 1973-2004, 2052-2085
helical OB fold Tower OB fold p.2481 p.2670 p.2831 p.3052 -2667 -2796 - 2872 -3186
TE D EP AC C
Cumulave incidence
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
BRCA1mut-L1780P BRCA1mut-BRCT
P = 0.012
BRCA1mut-ref
Age at diagnosis of breast cancer (years)
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT