- Email: [email protected]
Screening for gynaecological cancers
EJSO 32 (2006) 818e824
www.ejso.com
Screening for gynaecological cancers A. Sharma*, U. Menon a Department of Gynaecological Oncology, Institute of Women’s Health, University College London, 149, Tottenham Court Road, London W1T 7DN, UK Accepted 23 March 2006 Available online 8 May 2006
Abstract Background: The role of screening in gynaecological cancers is under evaluation. With mass screening proven effective in significantly reducing cervical cancer mortality, there is an interest in developing other screening methods to detect gynaecological malignancies early. This review covers advances in cervical cancer screening, strategies being investigated in ovarian cancer screening and the lack of justification in screening for endometrial, vulval and vaginal cancers. Methods: A Medline based literature search was performed for articles relating to screening for different gynaecological malignancies. Additional original papers cited in those identified by the initial search were also reviewed. Results: Advances in cervical cancer screening include liquid-based cytology and HPV testing. Results of ongoing trials are awaited before these can be fully implemented. The results of the two large, multicentre, randomised controlled trials being conducted in the United Kingdom and United States (UKCTOCS and PLCO study, respectively) to assess impact of screening on ovarian cancer mortality will shed some light on the need to implement screening for ovarian cancer in the general population. Novel markers, serum proteomic profiles and Doppler are some of the other technologies being explored. Currently, screening for endometrial cancer is not advocated as most women present with symptoms in early disease with good survival outcomes. Vulval and vaginal cancers are too rare to justify mass screening. Conclusion: Methods to screen for various gynaecological malignancies need further evaluation before implementation in the general population. Results of large multicentred trials are awaited. Presently, screening for endometrial, vaginal and vulval cancers is not justified. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Screening; Gynaecological malignancy; Ovarian neoplasm; Cervical cancer; Endometrial cancer
Introduction Screening is defined as a public health service for the apparently healthy population. A test is offered to identify individuals at risk in whom further investigations or treatment may minimize the risk of a particular disease or its complications.1 Though screening potentially saves or improves the quality of life through early detection of a serious condition, it is neither an absolute process nor does it guarantee protection. Cancer-screening programmes are based on the premise that the outcome will improve if disease is detected in early stages. There needs to be a suitable screening test that is acceptable to the population being screened and * Corresponding author. Tel: þ44 207 380 6915; fax: þ44 207 380 6929. E-mail address: [email protected] (A. Sharma). a Tel.: þ44 207 380 6908; fax: þ44 207 380 6929. 0748-7983/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejso.2006.03.034
effective treatment for the disease. The number of false positives and false negatives should be low and overall the programme should be cost effective. The most successful and well established screening programme is that for cervical cancer. This is well accepted and has significantly reduced mortality from the disease.2 Ovarian cancer is the other gynaecological malignancy that may justify screening as it fulfils many of the WHO screening criteria and there is some evidence that early detection of the disease may improve long term survival. Two large trials are currently being undertaken to assess the suitability, acceptability and cost-effectiveness of screening. In endometrial cancer, women generally present with symptoms in early disease and have a good outcome. Screening may not be as beneficial or justifiable. Vaginal and vulval cancers on the whole are quite rare to justify mass screening. Screening may be based on tumour markers, imaging techniques or a combination of both.
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Cervical cancer
Human papilloma virus (HPV)
Worldwide cervical cancer is the second leading malignant neoplasm in women. There has been a reduction in the incidence and mortality of cervical cancer in countries where there is an established screening programme.2 Screening for cervical cancer is mainly based on exfoliative cytology.3 Papanicolaou (Pap) smear screening can detect pre-invasive cervical cancer, thus, markedly reducing the incidence of invasive disease. Though this is an effective screening tool, it will not eradicate cervical cancer as the test lacks high sensitivity. In recent years, newer methods have been developed to improve detection.
Of all cervical cancers, 99% contain high-risk HPV. It is types 16, 18, 31, 33, 35, 45, 51, 52, 56 and 58 that are mainly associated with high-grade lesions and cervical cancer.9e11 Only where infection persists does cervical cancer occur. The role of HPV testing is being evaluated in primary screening for cervical cancer, triage of borderline and mildly dyskaryotic Pap smears and post-treatment followup of high-grade cervical intraepithelial neoplasia (CIN) and localized invasive disease. In primary screening, HPV DNA testing is more sensitive for prevalent high-grade CIN than either conventional or liquid cytology.12e17 The sensitivity for high-grade CIN ranges from 84 to 100% and the negative predictive value from 99.1 to 100%. A negative HPV test unlike negative cytology, almost excludes the possibility of highgrade lesions. This has been used to hypothesize that in women who are HPV negative and have a normal Pap smear, it maybe possible to (1) increase the screening interval18,19 and (2) if over the age of 50, discontinue screening.20 Data of cohort studies of elderly women with and without HPV infection as well as health-economical analyses to investigate the cost-effectiveness of the proposed hypothesis are still lacking. The period of time that a woman will remain in low risk after a negative HPV test result is presently unknown but is being studied by extended follow-up of previous and ongoing screening studies.21 The main disadvantage of HPV testing in primary screening is specificity. The specificity of HPV testing alone (73e95%) or in combination with cytology (68e 95%) is lower than that of cytology alone (88e99%).12e15 Most HPV infections are transient with 70% of high-risk HPV infections regressing within 3 years. HPV testing needs to be repeated or combined with conventional cytology to prevent over treatment of women with minor lesions where the likelihood of progression is low.18 In addition, the prevalence of HPV is higher (between 10 and 20%) in those aged under 30 and drops considerably after this age.22,23 Hence, HPV DNA testing below 30 years of age may result in an over diagnosis of cervical lesions that will probably regress spontaneously.24 HPV testing as a primary screening approach requires efficient management of HPV-positive women with negative or borderline cytology. In a UK multicentre primary screening study of 11,085 women aged 30e60 years, HPV testing with cytology for triage of HPV-positive women was found to potentially improve detection rates of high-grade CIN 2 without increasing the colposcopy referral rate. HPV-positive women with normal or borderline cytology (about 6% of screened women) were managed by repeat testing after 12 months.16 Mathematical modelling was used to simulate the natural history of HPV and cervical cancer in a cohort of US women aged over 30 years and to compare no screening and screening strategies at
Improvements in cytological testing Methods to improve cytological testing have been developed. Liquid-based cytology (LBC) involves a different slide preparation method by placing the specimen in a preservative fluid rather than directly on a slide. The sample is then utilised to form a thin layer of cells on a slide and is said to be more representative of the specimen. In this technique, nearly all cells are transferred to the fixative solution resulting in more satisfactory specimens, superior detection of infections and the prospect of carrying out multiple tests on the specimen, thus optimizing the effectiveness of primary cervical cancer screening.4,5 A metaanalysis of 14 studies has shown increased sensitivity (up to 12%) in detection of all grades of squamous intraepithelial lesions with liquid-based cytology in comparison to Pap smears.6 The main disadvantage is the need for more trained personnel and the increased expenses.4 A variety of commercial tests are available e Cytoscreen, Labonard Easy Prep, SurePath and ThinPrep with the latter two being most widely used.7 At present there is no recommendation on one method being better than the other. Three pilot studies have been carried out in England using LBC (ThinPrep in two sites and SurePath in the third site) and HPV testing to triage women with borderline and mildly dyskaryotic smears. One site using ThinPrep processed 30,000 smears whereas the other two processed 55,000 smears each. An interim report is available which addresses the effect and cost of LBC. The introduction of this technique resulted in a fall in inadequate smear rates from 9 to 1e2%, which was most significant in the site using SurePath.8 There was no clear evidence of any impact of LBC on detection rates of borderline or mildly dyskaryotic smears or on the overall detection rates of moderate and severe dyskaryosis across all sites. There was a reduction in the rate of smears showing glandular neoplasia but the implications of this could not be evaluated. There was a small reduction in overall cost of screening and treatment with LBC compared to conventional cytology.8 A similar pilot study is in progress in Wales.
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different frequencies with conventional cytology, liquidbased cytology with HPV testing for triage of equivocal results, and HPV DNA testing and cytology in combination. For women aged 30 years and more, every 2- or 3-year screening strategy that uses either HPV DNA testing in combination with cytology for primary screening or cytology with HPV DNA testing for equivocal results was found to provide a greater reduction in cancer and be less costly than annual conventional cytology.22 ARTISTIC (A Randomised Trial of HPV Testing in Primary Cervical Screening) is a UK study which commenced in 2001 and is investigating HPV as a primary screening test in 25,000 women aged 20e64 years attending general practices for routine cervical screening.25 The role of HPV in triage of borderline and mildly dyskaryotic cytology smears is under evaluation. In the large Atypical Squamous Cells of Undetermined Significance/ Low-grade Squamous Intraepithelial Lesions Triage Study (ALTS) involving 3488 women with atypical squamous cells of unknown significance (ASCUS) smears, a positive high-risk HPV DNA test identified 96% of women with high-grade lesions/cancer. The referral rate for colposcopy was 56%.26 The ALTS data have also shown that they require two liquid-based cytology tests to equal the sensitivity of one HPV test. HPV triage proved useful, with sensitivity equivalent to immediate colposcopy and led to halving of colposcopic referrals.27 Among older women with ASCUS, HPV testing remained sensitive for detecting CIN 3 and cancer, but the referral percentage was dramatically lower compared to younger women. Reduction of referral rates can only be achieved if the high negative predictive value of HPV infection is used to return women who have a negative HPV test and borderline cytology, to routine screening. There is controversy regarding the role of high-risk HPV testing in women with mild dyskaryosis.28 Some evidence suggested that HPV testing if used appropriately could safely reduce colposcopy referral rates. However, in the LSIL arm of the ALTS trial involving 1572 women, cytology was found to be very accurate and triaging by HPV testing in young women who have a very high rate of HPV DNA positivity (83%) was not cost effective.27 A UK multicentered trial evaluating the contribution of HPV testing to the effectiveness of the current management of women with mild or borderline dyskaryosis, TOMBOLA (Trial of Management of Borderline and Other Low grade Abnormal smears) has recruited 10,000 women aged between 20 and 59 years.25 Results will be available in 2007. In the absence of further data, incorporation of HPV testing into clinical practice should be exercised with caution. The value of HPV testing in follow-up after treatment of CIN has been assessed.15 It has been reported to be more sensitive than colposcopy.12,14 In a study of 130 women, its higher sensitivity and positive predictive rate compared to cytology significantly decreased the false positive rates
resulting in reduced colposcopy referrals, fewer reconization procedures and therefore reduced cost of screening per case of high-grade CIN detected.29 Currently available methods to test for HPV DNA are the Hybrid Capture 2 (HC2), which tests for 13 high-risk HPV types and the polymerase chain reaction (PCR) test. Testing for more than 10 HPV types decreases specificity more than it increases sensitivity.30 The development of Hybrid Capture 3 will offer enhanced HPV typing, as the robotics will allow greater test throughput. It is anticipated that PCR test improvements will contribute to the accuracy and cost-effectiveness of HPV DNA testing. A potential technique may be to combine HPV DNA testing with other markers such as proliferative or cell cycle regulatory proteins and then subdivide women who are HPV-positive into those who are at higher risk of cancer and those who can be safely followed up by screening at longer intervals.12 The feasibility of utilizing self-administered vaginal swabs as compared to cervical swabs for HPV DNA testing is also being investigated.31e34 Telomerase Telomerase is a cellular ribonucleoprotein reverse transcriptase. Studies have been done to investigate the usefulness of assaying telomerase activity as a possible screening marker for premalignant and malignant lesions of the cervix. In a study of 88 women, telomerase assay was reported to have a greater diagnostic accuracy than HPV-16/18 subtyping.35 However, a more recent study comparing telomerase activity assay and HPV-16 and 18 typing in detection of high-grade CIN has shown the assay to have poor sensitivity.36 Furthermore, larger studies need to be undertaken before any definite conclusions can be drawn. Other screening options Visual inspection of the cervix has been proposed as a method for the early detection of cervical cancer in developing countries where there is no organized mass screening programme and resources are limited. A study involving 2843 women was conducted in India to detect precursor lesions and cancer by direct visual method. Their results suggested that visual inspection as a screening method is not a reliable method to preselect women for cytology or be used as a low resource measure for cervical cancer screening in developing countries.37 Other studies agree that direct visual inspection is non-specific and thus unreliable method for screening. Superior visual methods such as cervicography and speculoscopy may be more specific and improve pick up of biopsy-confirmed cervical lesions, but the increase in time and cost-effectiveness of performing any of these procedures should be considered and justified before it can be included into routine practice.38,39 Another option being studied for low resource settings is performing visual inspection of the cervix after application of dilute acetic
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acid using a low threshold for referral with further investigation using HPV testing for those with abnormal looking lesions.18,40e42
Ovarian and fallopian tube cancer Ovarian cancer is the fourth commonest cause of cancer deaths and the leading cause for mortality from gynaecological malignancy in women in the developed countries. There is good evidence that diagnosis in early stage results in 5-year survival rates of over 90%, which supports the rationale for exploring screening for this disease. As no premalignant lesions have been identified so far, screening is limited to detecting low volume disease. Serum markers Tumour markers are biologic substances produced by malignant tumours that are measurable in circulation. Ideally, they should be tumour specific and have very high sensitivity, specificity and positive predictive value. They should be detectable in early disease and related to tumour load. However, their major limitation seems to be low specificity as they may be raised in various physiological or benign situations.43 The most widely used and assessed tumour marker for ovarian cancer is CA125. CA125 is an antigen expressed by coelomic epithelium and amnion during fetal development. It is not expressed by normal ovarian epithelium in either adult or fetus. In adults, it is found in tissue derived from coelomic and mullerian epithelium. CA125 is detected using a murine monoclonal antibody OC125 raised in response to antigenic determinants from an ovarian cancer cell line. Besides primary epithelial ovarian cancer, elevated levels may be noted in other malignancies such as pancreatic cancers and cancers of the breast and lung and in some benign conditions such as endometriosis, ectopic pregnancies, fibroids, arthritis and renal disease. In clinical practice, the commonly used cut-off for serum CA125 is 35 U/ml. Lower values of 25 U/ml or less may be more appropriate in postmenopausal women and those who have had a hysterectomy in the past.9e11 Elevated levels are found in 50% of patients with Stage I disease and >90% of women with more advanced stages.44 The initial screening strategy incorporated serum CA125 as a primary screen with pelvic ultrasound as a second line test to assess ovarian volume and morphology. Using this multimodal screening strategy, a sensitivity at 1 year of 78.6%, a specificity of 99.9% and positive predictive value of 26.8% (approximately four operations for each cancer) for detection of ovarian and fallopian tube cancer was achieved in 22,000 postmenopausal women.45 With the accumulation of data, ovarian morphology instead of volume has been used to refine algorithms for the interpretation of ultrasound.46 Sensitivity has been increased by
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developing a sophisticated statistical (Risk of Ovarian Cancer) algorithm to interpret CA125 levels. This is based on the findings that CA125 levels in women without ovarian cancer are static or decrease with time while levels associated with malignancy tend to rise. The algorithm incorporates age, age specific incidence of ovarian cancer, rate of change and absolute levels of CA125 to calculate an individual’s Risk of Ovarian Cancer. For a target specificity of 98%, the ROC calculation achieved a sensitivity of 86% for preclinical detection of ovarian cancer.47 This approach is part of the screening strategy in the ongoing UK Collaborative Trial of Ovarian Cancer Screening. There are many other tumour markers that are being assessed for screening. These include serum macrophage colony stimulating factor (M-CSF), prostasin, osteopontin, lysophosphatidic acid (LPA), serum inhibin, and human kallikrein especially hK6 and hK10.9,48e50 Recent studies have shown that integrin-linked kinase (irILK) expression, a tumour associated antigen, is present in 6e9-fold higher levels in serum of patients with ovarian cancer compared to the serum of healthy women and those with benign ovarian tumours.51 Surface-enhanced laser desorption ionization time-offlight (SELDI-TOF) and artificial-intelligence-based informatics algorithms have identified a set of key protein values and are able to discriminate normal from ovarian cancer patients. Serum proteomic pattern analysis is being extensively studied in ovarian cancer and might ultimately lead to an ideal marker for screening.9,48e50 Transvaginal scanning Transvaginal scanning is being investigated as both a first line and a second line method in conjunction with CA125 for screening for ovarian cancer.46,52 The transvaginal route is preferred as it gives a more precise image of the ovary. Both ovarian volume and morphology are assessed with cut-offs for volume ranging from 10 ml to 20 ml depending on menopausal status. Persistence of abnormalities on repeat scanning 4e6 weeks following initial detection helps reduce false positive rates. The lack of physiological changes in ovarian volume in postmenopausal women further decreases the number of false positives in this group compared to premenopausal women. However, even in older women there is a high prevalence of benign ovarian lesions. Complex morphology has been used in various screening protocols to assist in reduction of false positives.9e11,53 Both subjective assessment of the grey scale images and weighted scoring systems or morphological indices based on ovarian volume, outline, presence of papillary projections and cyst complexity (i.e. number of locules, wall structure, thickness of septae and echogenecity of fluid) have been explored. Based on gross anatomic changes at the time of surgery, papillary projections have the highest and simple cysts and septal thickness the lowest correlation with a diagnosis of ovarian malignancy.54 There is a definite
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move to manage simple cysts and multilocular cysts conservatively in these apparently healthy postmenopausal women. Numerous studies have looked at whether Doppler will decrease the false positive rates. The rationale is that blood flow patterns are altered in neoplastic tissue and this should assist in their differentiation from physiological and benign conditions of the ovary. Some of these studies have shown that transvaginal ultrasonography is quite precise in distinguishing benign from malignant ovarian tumours and accurately defines the morphological and vascular features of ovarian lesions. However, color flow Doppler findings are not specific enough to be used independent of grey-scale ultrasonography. The specificity does, however, improve significantly with the addition of 3D power Doppler.55,56 Other tests that may be used in distinguishing benign from malignant ovarian lesions are computerized tomography and magnetic resonance imaging. Overall, the data from large prospective studies of screening for ovarian cancer suggest that sequential multimodal screening has superior specificity and positive predictive value compared to strategies based on transvaginal ultrasound alone. However, ultrasound as a first line test may offer greater sensitivity for early stage disease. Target populations and current screening trials A vital part of any screening strategy is identifying the population at risk of developing the disease. The two main populations at increased risk for ovarian cancer are women from the general population aged 50 years or more (90% of the disease occurs in this group) and those aged 35 years or more with a familial risk (based on their family history).57 In both these populations, trials are underway to assess the risks and benefits of screening. In the general population, there are two major randomised controlled trials being undertaken to assess the impact of screening on ovarian cancer mortality. The UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) aims to randomly allocate 200,000 postmenopausal women to a control group (100,000) or screening for 6 years. In the screening arm, two strategies are being tested. Primary screening using CA125 with transvaginal ultrasound as the second line test (multimodal screening, 50,000) or ultrasound screening (50,000).57 The principal end point of the study is death from ovarian cancer. Cost-effectiveness, physical and psychological morbidity, compliance and acceptability of screening are also being studied. Totally 180,000 postmenopausal women have been recruited from 13 centres in the United Kingdom. All participants will be followed up for 7 years via the Office of National Statistics and postal questionnaire. The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial in the United States, has recruited 74,000 women (37,000 in the screen arm and the same number in the nonscreen arm) and will compare a control group with a screened
group undergoing primary screening with both CA125 testing and transvaginal ultrasonography for 3 years followed by CA125 testing alone for a further 2 years. These women will be followed up annually for 13 years following randomisation.58,59 Results of these trials (UKCTOCS in 2012 and PLCO in 2015) should provide information on whether mass screening for ovarian cancer should be implemented. Women were considered at high risk for familial ovarian cancer if they have more than one first-degree relative with ovarian cancer or a combination of early breast and ovarian cancers. Majority of familial ovarian cancer is due to inherited mutations in the BRCA1/BRCA2 breasteovarian cancer susceptibility genes with a small proportion associated with hereditary nonpolyposis colorectal cancer (HNPCC) syndrome. Gene testing is now widely available. However, there are still no definitive answers on how best to manage the ovarian cancer risk in these women. Prophylactic salpingo-oophorectomy has been shown to reduce the risk of ovarian cancer by more than 95% and the breast cancer risk by 50%.57,60,61 Some women, however, would prefer to avoid prophylactic surgery and screening trials are underway in this population. Such trials (UK Familial Ovarian Cancer Screening Study, UKFOCSS, CGN highrisk study and the GOG study in the USA) usually involve screening with CA125 and transvaginal ultrasound in highrisk women over 35 years of age. Many of these women are premenopausal and prone to both physiological and benign conditions that may result in false positive results on ultrasound and CA125 testing. It is important that this population is aware that there is no evidence at present to show that screening can reduce mortality.57 The low prevalence of ovarian cancer means that specificity of the screening strategies must be very high to maintain a reasonable false positive rate. In addition, as women with screen positive results need surgical investigation, the false positive rates of the various strategies available will significantly impact on the overall benefits of ovarian cancer screening.62
Endometrial cancer Endometrial cancer is the most common cancer of the genital tract and represents 10% of all cancers diagnosed in women.63 Most women present with abnormal bleeding in early stage and hence screening for this condition is not currently recommended either in the general population or in women at increased risk due to obesity, infertility or diabetes or use of tamoxifen.64,65 In breast cancer patients on tamoxifen, screening of endometrium using pipelle biopsy has been explored.66 However, further evaluation of routine office endometrial biopsy is required before recommending it as a standard screening test for breast cancer patients on tamoxifen.67,68 Currently, screening is only advocated for women at high risk of the disease due to genetic predisposition
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resulting from hereditary nonpolyposis colorectal cancer (HNPCC) syndrome. The lifetime risk of endometrial cancer in these women can be 40e60%.69,70 These women should be counselled for prophylactic hysterectomy and bilateral salpingo-oophorectomy, if prophylactic colectomy is planned, especially if they have already completed their families. Some studies show that the survival from endometrial cancer in the general population does not significantly differ from women with or at a risk from HNPCC.71 Annual measurement of endometrial thickness using TVS is the most commonly used screening test for this high-risk population. Using a cut-off of 4 mm for endometrial thickness, the sensitivity for detecting endometrial cancer is 98% and the negative predictive value is 99%.9,48e50,72 So far, improved pick up of premalignant and malignant endometrial lesions by Dopplers has not been shown.72 Endometrial pipelle biopsy and hysteroscopy with directed biopsy are used as second line tests. In postmenopausal women, presence of endometrial cells (normal or abnormal) in a Pap smear should raise the suspicion of endometrial cancer.73 However, the test has low sensitivity. K ras mutations have been detected in 10e30% of endometrial cancers on Pap smears from women with these tumours.9,48e50 This raises the possibility of using these and other oncogenes and suppressor genes as markers for detecting endometrial cancers in cervical smears.74 Telomerase expression is noted in a normal menstrual cycle.75 However, activity is either weak or absent in postmenopausal women. As endometrial cancers express telomerase strongly, assay of activity in smears from postmenopausal women has been explored as a screening test for the disease.76
Vulval and vaginal cancer These are rare cancers and sparse literature is available regarding these. Some studies have shown elevation of tissue polypeptide specific antigen (TPS), SCC and urinary core fragment of the beta subunit of HCG. The value of screening has not been explored.43
References 1. What is screening? http://www.nsc.nhs.uk/. 2. Cervical screening has reduced incidence of cancer and mortality. BMJ 1999;318(7188): 0. 3. Sasieni P, Adams J. Effect of screening on cervical cancer mortality in England and Wales: analysis of trends with an age period cohort model. BMJ 1999;318(7193):1244–5. 4. McNeeley Jr SG. New cervical cancer screening techniques. Am J Obstet Gynecol 2003;189(4 Suppl):S40–1. 5. Monsonego J, Autillo-Touati A, Bergeron C, et al. Liquid phase cytology in the primary screening for cervical cancer: a multicenter study. Gynecol Obstet Fertil 2001;29(11):799–807. 6. NICE. Full guidance on the use of liquid-based cytology for cervical screening (review), 2003.
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7. 2003/54 NICE guidance on liquid based cytology contributes to modernisation of cervical screening services for women. NICE; 2003. 8. Moss S, Gray A, Legood R, Henstock E. First report to the department of health on evaluation of LBC 2002. 9. Menon U, Jacobs IJ. Tumor markers and screening. 4th ed. 2003. 10. Shvartsman HS, Lu KH, Lee J, et al. Overexpression of kallikrein 10 in epithelial ovarian carcinomas. Gynecol Oncol 2003;90(1):44–50. 11. Ni X, Zhang W, Huang KC, et al. Characterisation of human kallikrein 6/protease M expression in ovarian cancer. Br J Cancer 2004;91(4): 725–31. 12. Lorincz AT. Screening for cervical cancer: new alternatives and research. Salud Publica Mex 2003;45(Suppl 3):S376–87. 13. Nieminen P, Vuorma S, Viikki M, Hakama M, Anttila A. Comparison of HPV test versus conventional and automation-assisted Pap screening as potential screening tools for preventing cervical cancer. BJOG 2004;111(8):842–8. 14. Petry KU, Menton S, Menton M, et al. Inclusion of HPV testing in routine cervical cancer screening for women above 29 years in Germany: results for 8466 patients. Br J Cancer 2003;88(10):1570–7. 15. Franco EL. Chapter 13: Primary screening of cervical cancer with human papillomavirus tests. J Natl Cancer Inst Monogr 2003;31:89–96. 16. Cuzick J, Szarewski A, Cubie H, et al. Management of women who test positive for high-risk types of human papillomavirus: the HART study. Lancet 2003;362(9399):1871–6. 17. Cuzick J, Szarewski A, Terry G, et al. Human papillomavirus testing in primary cervical screening. Lancet 1995;345(8964):1533–6. 18. Sasieni PD. Human papillomavirus screening and cervical cancer prevention. J Am Med Womens Assoc 2000;55(4):216–9. 19. Schiffman M, Castle PE. Human papillomavirus: epidemiology and public health. Arch Pathol Lab Med 2003;127(8):930–4. 20. Baay MF, Smits E, Tjalma WA, et al. Can cervical cancer screening be stopped at 50? The prevalence of HPV in elderly women. Int J Cancer 2004;108(2):258–61. 21. Franco EL. Are we ready for a paradigm change in cervical cancer screening? Lancet 2003;362(9399):1866–7. 22. Goldie SJ, Kim JJ, Wright TC. Cost-effectiveness of human papillomavirus DNA testing for cervical cancer screening in women aged 30 years or more. Obstet Gynecol 2004;103(4):619–31. 23. Holmes J, Hemmett L, Garfield S. The cost-effectiveness of human papillomavirus screening for cervical cancer. A review of recent modelling studies. Eur J Health Econ 2005;6(1):30–7. 24. Saslow D, Runowicz CD, Solomon D, et al. American Cancer Society guideline for the early detection of cervical neoplasia and cancer. CA Cancer J Clin 2002;52(6):342–62. 25. Human Papilloma Virus (HPV). http://www.cancerscreening.nhs.uk/ cervical/hpv.html 26. Schiffman M, Solomon D. Findings to date from the ASCUSeLSIL Triage Study (ALTS). Arch Pathol Lab Med 2003;127(8):946–9. 27. Cox JT. The clinician’s view: role of human papillomavirus testing in the American Society for Colposcopy and Cervical Pathology Guidelines for the management of abnormal cervical cytology and cervical cancer precursors. Arch Pathol Lab Med 2003;127(8):950–8. 28. Cuzick J, Sasieni P, Davies P, et al. A systematic review of the role of human papilloma virus (HPV) testing within a cervical screening programme: summary and conclusions. Br J Cancer 2000;83(5):561–5. 29. Almog B, Gamzu R, Bornstein J, et al. Clinical and economic benefit of HPV-load testing in follow-up and management of women postcone biopsy for CIN2-3. Br J Cancer 2003;89(1):109–12. 30. Schiffman M, Khan MJ, Solomon D, et al. A study of the impact of adding HPV types to cervical cancer screening and triage tests. J Natl Cancer Inst 2005;97(2):147–50. 31. Finan RR, Irani-Hakime N, Tamim H, Almawi WY. Validity of vaginal testing in detecting human papillomavirus (HPV) genotypes. J Clin Virol 2000;19(3):163–8. 32. Palmisano ME, Gaffga AM, Daigle J, et al. Detection of human papillomavirus DNA in self-administered vaginal swabs as compared to cervical swabs. Int J STD AIDS 2003;14(8):560–7.
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33. Gravitt PE, Lacey Jr JV, Brinton LA, et al. Evaluation of self-collected cervicovaginal cell samples for human papillomavirus testing by polymerase chain reaction. Cancer Epidemiol Biomarkers Prev 2001; 10(2):95–100. 34. Harper DM, Hildesheim A, Cobb JL, Greenberg M, Vaught J, Lorincz AT. Collection devices for human papillomavirus. J Fam Pract 1999;48(7):531–5. 35. Reddy VG, Khanna N, Jain SK, Das BC, Singh N. Telomerase e a molecular marker for cervical cancer screening. Int J Gynecol Cancer 2001;11(2):100–6. 36. Ngan HY, Cheung AN, Liu SS, Liu KL, Tsao SW. Telomerase assay and HPV 16/18 typing as adjunct to conventional cytological cervical cancer screening. Tumour Biol 2002;23(2):87–92. 37. Wesley R, Sankaranarayanan R, Mathew B, et al. Evaluation of visual inspection as a screening test for cervical cancer. Br J Cancer 1997; 75(3):436–40. 38. Wright Jr TC, Denny L, Kuhn L, Goldie S. Use of visual screening methods for cervical cancer screening. Obstet Gynecol Clin North Am 2002;29(4):701–34. 39. Ferris DG, Payne P, Frisch LE, Milner FH, diPaola FM, Petry LJ. Cervicography: adjunctive cervical cancer screening by primary care clinicians. J Fam Pract 1993;37(2):158–64. 40. Suba EJ, Raab SS. Direct visual inspection for cervical cancer screening. Cancer 2004;101(10):2365 [author reply 2366]. 41. Gaffikin L, Lauterbach M, Blumenthal PD. Performance of visual inspection with acetic acid for cervical cancer screening: a qualitative summary of evidence to date. Obstet Gynecol Surv 2003;58(8): 543–50. 42. Belinson JL, Pretorius RG, Zhang WH, Wu LY, Qiao YL, Elson P. Cervical cancer screening by simple visual inspection after acetic acid. Obstet Gynecol 2001;98(3):441–4. 43. Menon U, Jacobs IJ. Tumor markers. 3rd ed. LWW; 2000. 44. Fritsche HA, Bast RC. CA 125 in ovarian cancer: advances and controversy. Clin Chem 1998;44(7):1379–80. 45. Jacobs I, Davies AP, Bridges J, et al. Prevalence screening for ovarian cancer in postmenopausal women by CA 125 measurement and ultrasonography. BMJ 1993;306(6884):1030–4. 46. Menon U, Talaat A, Rosenthal AN, et al. Performance of ultrasound as a second line test to serum CA125 in ovarian cancer screening. BJOG 2000;107(2):165–9. 47. Skates SJ, Menon U, MacDonald N, et al. Calculation of the risk of ovarian cancer from serial CA-125 values for preclinical detection in postmenopausal women. J Clin Oncol 2003;21(Suppl. 10):206–10. 48. Ardekani AM, Liotta LA, Petricoin 3rd EF. Clinical potential of proteomics in the diagnosis of ovarian cancer. Expert Rev Mol Diagn 2002;2(4):312–20. 49. Bandera CA, Ye B, Mok SC. New technologies for the identification of markers for early detection of ovarian cancer. Curr Opin Obstet Gynecol 2003;15(1):51–5. 50. Markman M, Belinson J, Webster K, et al. Phase 2 trial of interferonbeta as second-line treatment of ovarian cancer, fallopian tube cancer, or primary carcinoma of the peritoneum. Oncology 2004;66(5):343–6. 51. Ahmed N, Oliva K, Rice GE, Quinn MA. Cell-free 59 kDa immunoreactive integrin-linked kinase: a novel marker for ovarian carcinoma. Clin Cancer Res 2004;10(7):2415–20. 52. Chappuis PO, Narod SA, Foulkes WD. Screening for ovarian cancer. Lancet 1999;354(9177):509–10. 53. Diamandis EP, Scorilas A, Fracchioli S, et al. Human kallikrein 6 (hK6): a new potential serum biomarker for diagnosis and prognosis of ovarian carcinoma. J Clin Oncol 2003;21(6):1035–43. 54. Granberg S, Wikland M, Jansson I. Macroscopic characterization of ovarian tumors and the relation to the histological diagnosis: criteria to be used for ultrasound evaluation. Gynecol Oncol 1989;35(2):139–44.
55. Carter JR, Lau M, Fowler JM, Carlson JW, Carson LF, Twiggs LB. Blood flow characteristics of ovarian tumors: implications for ovarian cancer screening. Am J Obstet Gynecol 1995;172(3):901–7. 56. Cohen LS, Escobar PF, Scharm C, Glimco B, Fishman DA. Three-dimensional power Doppler ultrasound improves the diagnostic accuracy for ovarian cancer prediction. Gynecol Oncol 2001;82(1): 40–8. 57. Menon U. Ovarian cancer screening. CMAJ 2004;171(4):323–4. 58. Andriole GL, Reding D, Hayes RB, Prorok PC, Gohagan JK. The prostate, lung, colon, and ovarian (PLCO) cancer screening trial: status and promise. Urol Oncol 2004;22(4):358–61. 59. Hayes RB, Reding D, Kopp W, et al. Etiologic and early marker studies in the prostate, lung, colorectal and ovarian (PLCO) cancer screening trial. Control Clin Trials 2000;21(Suppl. 6):349S–55S. 60. Rebbeck TR. Prophylactic oophorectomy in BRCA1 and BRCA2 mutation carriers. Eur J Cancer 2002;38(Suppl. 6):S15–7. 61. Rebbeck TR, Lynch HT, Neuhausen SL, et al. Prophylactic oophorectomy in carriers of BRCA1 or BRCA2 mutations. N Engl J Med 2002; 346(21):1616–22. 62. Bell R, Petticrew M, Luengo S, Sheldon TA. Screening for ovarian cancer: a systematic review. Health Technol Assess 1998;2(2):i–iv, 1e84. 63. Baiocchi G, Gilardi G. Endometrial carcinoma: an increasing neoplasm. Screening and early diagnosis: proposal for a protocol. Minerva Ginecol 1997;49(4):147–52. 64. Chlebowski RT, Collyar DE, Somerfield MR, Pfister DG. American Society of Clinical Oncology technology assessment on breast cancer risk reduction strategies: tamoxifen and raloxifene. J Clin Oncol 1999; 17(6):1939–55. 65. ACOG committee opinion: tamoxifen and endometrial cancer. Int J Gynaecol Obstet 2001;73(1):77–9. 66. Berliere M, Charles A, Galant C, Donnez J. Uterine side effects of tamoxifen: a need for systematic pretreatment screening. Obstet Gynecol 1998;91(1):40–4. 67. Barakat RR. Benign and hyperplastic endometrial changes associated with tamoxifen use. Oncology (Huntingt) 1997;11(2 Suppl. 1):35–7. 68. Barakat RR. Screening for endometrial cancer in the patient receiving tamoxifen for breast cancer. J Clin Oncol 1999;17(7):1967–8. 69. Huang D, Chen C, Sun W, Strom CM, Bender RA. High-throughput gene sequencing assay development for hereditary nonpolyposis colon cancer. Clin Colorectal Cancer 2004;4(4):275–9. 70. Chung L, Broaddus R, Crozier M, Luthraa R, Levenback C, Lu K. Unexpected endometrial cancer at prophylactic hysterectomy in a woman with hereditary nonpolyposis colon cancer. Obstet Gynecol 2003; 102(5 Pt 2):1152–5. 71. Boks DE, Trujillo AP, Voogd AC, Morreau H, Kenter GG, Vasen HF. Survival analysis of endometrial carcinoma associated with hereditary nonpolyposis colorectal cancer. Int J Cancer 2002;102(2):198–200. 72. Barik S, Tidy J. Screening for endometrial cancer in asymptomatic postmenopausal women with conventional and colour Doppler sonography. Br J Obstet Gynaecol 1999;106(11):1229–30. 73. Zygmunt A, Markowska J, Fischer N. Significance of tissue polypeptide specific antigen (TPS) in diagnosis and monitoring of treatment in ovarian cancer. Eur J Gynaecol Oncol 1998;19(5):484–6. 74. Al-Jehani RM, Jeyarajah AR, Hagen B, Hogdall EV, Oram DH, Jacobs IJ. Model for the molecular genetic diagnosis of endometrial cancer using K-ras mutation analysis. J Natl Cancer Inst 1998;90(7): 540–2. 75. Yokoyama Y, Takahashi Y, Morishita S, Hashimoto M, Niwa K, Tamaya T. Telomerase activity in the human endometrium throughout the menstrual cycle. Mol Hum Reprod 1998;4(2):173–7. 76. Zheng PS, Iwasaka T, Yamasaki F, et al. Telomerase activity in gynecologic tumors. Gynecol Oncol 1997;64(1):171–5.
www.ejso.com
Screening for gynaecological cancers A. Sharma*, U. Menon a Department of Gynaecological Oncology, Institute of Women’s Health, University College London, 149, Tottenham Court Road, London W1T 7DN, UK Accepted 23 March 2006 Available online 8 May 2006
Abstract Background: The role of screening in gynaecological cancers is under evaluation. With mass screening proven effective in significantly reducing cervical cancer mortality, there is an interest in developing other screening methods to detect gynaecological malignancies early. This review covers advances in cervical cancer screening, strategies being investigated in ovarian cancer screening and the lack of justification in screening for endometrial, vulval and vaginal cancers. Methods: A Medline based literature search was performed for articles relating to screening for different gynaecological malignancies. Additional original papers cited in those identified by the initial search were also reviewed. Results: Advances in cervical cancer screening include liquid-based cytology and HPV testing. Results of ongoing trials are awaited before these can be fully implemented. The results of the two large, multicentre, randomised controlled trials being conducted in the United Kingdom and United States (UKCTOCS and PLCO study, respectively) to assess impact of screening on ovarian cancer mortality will shed some light on the need to implement screening for ovarian cancer in the general population. Novel markers, serum proteomic profiles and Doppler are some of the other technologies being explored. Currently, screening for endometrial cancer is not advocated as most women present with symptoms in early disease with good survival outcomes. Vulval and vaginal cancers are too rare to justify mass screening. Conclusion: Methods to screen for various gynaecological malignancies need further evaluation before implementation in the general population. Results of large multicentred trials are awaited. Presently, screening for endometrial, vaginal and vulval cancers is not justified. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Screening; Gynaecological malignancy; Ovarian neoplasm; Cervical cancer; Endometrial cancer
Introduction Screening is defined as a public health service for the apparently healthy population. A test is offered to identify individuals at risk in whom further investigations or treatment may minimize the risk of a particular disease or its complications.1 Though screening potentially saves or improves the quality of life through early detection of a serious condition, it is neither an absolute process nor does it guarantee protection. Cancer-screening programmes are based on the premise that the outcome will improve if disease is detected in early stages. There needs to be a suitable screening test that is acceptable to the population being screened and * Corresponding author. Tel: þ44 207 380 6915; fax: þ44 207 380 6929. E-mail address: [email protected] (A. Sharma). a Tel.: þ44 207 380 6908; fax: þ44 207 380 6929. 0748-7983/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejso.2006.03.034
effective treatment for the disease. The number of false positives and false negatives should be low and overall the programme should be cost effective. The most successful and well established screening programme is that for cervical cancer. This is well accepted and has significantly reduced mortality from the disease.2 Ovarian cancer is the other gynaecological malignancy that may justify screening as it fulfils many of the WHO screening criteria and there is some evidence that early detection of the disease may improve long term survival. Two large trials are currently being undertaken to assess the suitability, acceptability and cost-effectiveness of screening. In endometrial cancer, women generally present with symptoms in early disease and have a good outcome. Screening may not be as beneficial or justifiable. Vaginal and vulval cancers on the whole are quite rare to justify mass screening. Screening may be based on tumour markers, imaging techniques or a combination of both.
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Cervical cancer
Human papilloma virus (HPV)
Worldwide cervical cancer is the second leading malignant neoplasm in women. There has been a reduction in the incidence and mortality of cervical cancer in countries where there is an established screening programme.2 Screening for cervical cancer is mainly based on exfoliative cytology.3 Papanicolaou (Pap) smear screening can detect pre-invasive cervical cancer, thus, markedly reducing the incidence of invasive disease. Though this is an effective screening tool, it will not eradicate cervical cancer as the test lacks high sensitivity. In recent years, newer methods have been developed to improve detection.
Of all cervical cancers, 99% contain high-risk HPV. It is types 16, 18, 31, 33, 35, 45, 51, 52, 56 and 58 that are mainly associated with high-grade lesions and cervical cancer.9e11 Only where infection persists does cervical cancer occur. The role of HPV testing is being evaluated in primary screening for cervical cancer, triage of borderline and mildly dyskaryotic Pap smears and post-treatment followup of high-grade cervical intraepithelial neoplasia (CIN) and localized invasive disease. In primary screening, HPV DNA testing is more sensitive for prevalent high-grade CIN than either conventional or liquid cytology.12e17 The sensitivity for high-grade CIN ranges from 84 to 100% and the negative predictive value from 99.1 to 100%. A negative HPV test unlike negative cytology, almost excludes the possibility of highgrade lesions. This has been used to hypothesize that in women who are HPV negative and have a normal Pap smear, it maybe possible to (1) increase the screening interval18,19 and (2) if over the age of 50, discontinue screening.20 Data of cohort studies of elderly women with and without HPV infection as well as health-economical analyses to investigate the cost-effectiveness of the proposed hypothesis are still lacking. The period of time that a woman will remain in low risk after a negative HPV test result is presently unknown but is being studied by extended follow-up of previous and ongoing screening studies.21 The main disadvantage of HPV testing in primary screening is specificity. The specificity of HPV testing alone (73e95%) or in combination with cytology (68e 95%) is lower than that of cytology alone (88e99%).12e15 Most HPV infections are transient with 70% of high-risk HPV infections regressing within 3 years. HPV testing needs to be repeated or combined with conventional cytology to prevent over treatment of women with minor lesions where the likelihood of progression is low.18 In addition, the prevalence of HPV is higher (between 10 and 20%) in those aged under 30 and drops considerably after this age.22,23 Hence, HPV DNA testing below 30 years of age may result in an over diagnosis of cervical lesions that will probably regress spontaneously.24 HPV testing as a primary screening approach requires efficient management of HPV-positive women with negative or borderline cytology. In a UK multicentre primary screening study of 11,085 women aged 30e60 years, HPV testing with cytology for triage of HPV-positive women was found to potentially improve detection rates of high-grade CIN 2 without increasing the colposcopy referral rate. HPV-positive women with normal or borderline cytology (about 6% of screened women) were managed by repeat testing after 12 months.16 Mathematical modelling was used to simulate the natural history of HPV and cervical cancer in a cohort of US women aged over 30 years and to compare no screening and screening strategies at
Improvements in cytological testing Methods to improve cytological testing have been developed. Liquid-based cytology (LBC) involves a different slide preparation method by placing the specimen in a preservative fluid rather than directly on a slide. The sample is then utilised to form a thin layer of cells on a slide and is said to be more representative of the specimen. In this technique, nearly all cells are transferred to the fixative solution resulting in more satisfactory specimens, superior detection of infections and the prospect of carrying out multiple tests on the specimen, thus optimizing the effectiveness of primary cervical cancer screening.4,5 A metaanalysis of 14 studies has shown increased sensitivity (up to 12%) in detection of all grades of squamous intraepithelial lesions with liquid-based cytology in comparison to Pap smears.6 The main disadvantage is the need for more trained personnel and the increased expenses.4 A variety of commercial tests are available e Cytoscreen, Labonard Easy Prep, SurePath and ThinPrep with the latter two being most widely used.7 At present there is no recommendation on one method being better than the other. Three pilot studies have been carried out in England using LBC (ThinPrep in two sites and SurePath in the third site) and HPV testing to triage women with borderline and mildly dyskaryotic smears. One site using ThinPrep processed 30,000 smears whereas the other two processed 55,000 smears each. An interim report is available which addresses the effect and cost of LBC. The introduction of this technique resulted in a fall in inadequate smear rates from 9 to 1e2%, which was most significant in the site using SurePath.8 There was no clear evidence of any impact of LBC on detection rates of borderline or mildly dyskaryotic smears or on the overall detection rates of moderate and severe dyskaryosis across all sites. There was a reduction in the rate of smears showing glandular neoplasia but the implications of this could not be evaluated. There was a small reduction in overall cost of screening and treatment with LBC compared to conventional cytology.8 A similar pilot study is in progress in Wales.
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different frequencies with conventional cytology, liquidbased cytology with HPV testing for triage of equivocal results, and HPV DNA testing and cytology in combination. For women aged 30 years and more, every 2- or 3-year screening strategy that uses either HPV DNA testing in combination with cytology for primary screening or cytology with HPV DNA testing for equivocal results was found to provide a greater reduction in cancer and be less costly than annual conventional cytology.22 ARTISTIC (A Randomised Trial of HPV Testing in Primary Cervical Screening) is a UK study which commenced in 2001 and is investigating HPV as a primary screening test in 25,000 women aged 20e64 years attending general practices for routine cervical screening.25 The role of HPV in triage of borderline and mildly dyskaryotic cytology smears is under evaluation. In the large Atypical Squamous Cells of Undetermined Significance/ Low-grade Squamous Intraepithelial Lesions Triage Study (ALTS) involving 3488 women with atypical squamous cells of unknown significance (ASCUS) smears, a positive high-risk HPV DNA test identified 96% of women with high-grade lesions/cancer. The referral rate for colposcopy was 56%.26 The ALTS data have also shown that they require two liquid-based cytology tests to equal the sensitivity of one HPV test. HPV triage proved useful, with sensitivity equivalent to immediate colposcopy and led to halving of colposcopic referrals.27 Among older women with ASCUS, HPV testing remained sensitive for detecting CIN 3 and cancer, but the referral percentage was dramatically lower compared to younger women. Reduction of referral rates can only be achieved if the high negative predictive value of HPV infection is used to return women who have a negative HPV test and borderline cytology, to routine screening. There is controversy regarding the role of high-risk HPV testing in women with mild dyskaryosis.28 Some evidence suggested that HPV testing if used appropriately could safely reduce colposcopy referral rates. However, in the LSIL arm of the ALTS trial involving 1572 women, cytology was found to be very accurate and triaging by HPV testing in young women who have a very high rate of HPV DNA positivity (83%) was not cost effective.27 A UK multicentered trial evaluating the contribution of HPV testing to the effectiveness of the current management of women with mild or borderline dyskaryosis, TOMBOLA (Trial of Management of Borderline and Other Low grade Abnormal smears) has recruited 10,000 women aged between 20 and 59 years.25 Results will be available in 2007. In the absence of further data, incorporation of HPV testing into clinical practice should be exercised with caution. The value of HPV testing in follow-up after treatment of CIN has been assessed.15 It has been reported to be more sensitive than colposcopy.12,14 In a study of 130 women, its higher sensitivity and positive predictive rate compared to cytology significantly decreased the false positive rates
resulting in reduced colposcopy referrals, fewer reconization procedures and therefore reduced cost of screening per case of high-grade CIN detected.29 Currently available methods to test for HPV DNA are the Hybrid Capture 2 (HC2), which tests for 13 high-risk HPV types and the polymerase chain reaction (PCR) test. Testing for more than 10 HPV types decreases specificity more than it increases sensitivity.30 The development of Hybrid Capture 3 will offer enhanced HPV typing, as the robotics will allow greater test throughput. It is anticipated that PCR test improvements will contribute to the accuracy and cost-effectiveness of HPV DNA testing. A potential technique may be to combine HPV DNA testing with other markers such as proliferative or cell cycle regulatory proteins and then subdivide women who are HPV-positive into those who are at higher risk of cancer and those who can be safely followed up by screening at longer intervals.12 The feasibility of utilizing self-administered vaginal swabs as compared to cervical swabs for HPV DNA testing is also being investigated.31e34 Telomerase Telomerase is a cellular ribonucleoprotein reverse transcriptase. Studies have been done to investigate the usefulness of assaying telomerase activity as a possible screening marker for premalignant and malignant lesions of the cervix. In a study of 88 women, telomerase assay was reported to have a greater diagnostic accuracy than HPV-16/18 subtyping.35 However, a more recent study comparing telomerase activity assay and HPV-16 and 18 typing in detection of high-grade CIN has shown the assay to have poor sensitivity.36 Furthermore, larger studies need to be undertaken before any definite conclusions can be drawn. Other screening options Visual inspection of the cervix has been proposed as a method for the early detection of cervical cancer in developing countries where there is no organized mass screening programme and resources are limited. A study involving 2843 women was conducted in India to detect precursor lesions and cancer by direct visual method. Their results suggested that visual inspection as a screening method is not a reliable method to preselect women for cytology or be used as a low resource measure for cervical cancer screening in developing countries.37 Other studies agree that direct visual inspection is non-specific and thus unreliable method for screening. Superior visual methods such as cervicography and speculoscopy may be more specific and improve pick up of biopsy-confirmed cervical lesions, but the increase in time and cost-effectiveness of performing any of these procedures should be considered and justified before it can be included into routine practice.38,39 Another option being studied for low resource settings is performing visual inspection of the cervix after application of dilute acetic
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acid using a low threshold for referral with further investigation using HPV testing for those with abnormal looking lesions.18,40e42
Ovarian and fallopian tube cancer Ovarian cancer is the fourth commonest cause of cancer deaths and the leading cause for mortality from gynaecological malignancy in women in the developed countries. There is good evidence that diagnosis in early stage results in 5-year survival rates of over 90%, which supports the rationale for exploring screening for this disease. As no premalignant lesions have been identified so far, screening is limited to detecting low volume disease. Serum markers Tumour markers are biologic substances produced by malignant tumours that are measurable in circulation. Ideally, they should be tumour specific and have very high sensitivity, specificity and positive predictive value. They should be detectable in early disease and related to tumour load. However, their major limitation seems to be low specificity as they may be raised in various physiological or benign situations.43 The most widely used and assessed tumour marker for ovarian cancer is CA125. CA125 is an antigen expressed by coelomic epithelium and amnion during fetal development. It is not expressed by normal ovarian epithelium in either adult or fetus. In adults, it is found in tissue derived from coelomic and mullerian epithelium. CA125 is detected using a murine monoclonal antibody OC125 raised in response to antigenic determinants from an ovarian cancer cell line. Besides primary epithelial ovarian cancer, elevated levels may be noted in other malignancies such as pancreatic cancers and cancers of the breast and lung and in some benign conditions such as endometriosis, ectopic pregnancies, fibroids, arthritis and renal disease. In clinical practice, the commonly used cut-off for serum CA125 is 35 U/ml. Lower values of 25 U/ml or less may be more appropriate in postmenopausal women and those who have had a hysterectomy in the past.9e11 Elevated levels are found in 50% of patients with Stage I disease and >90% of women with more advanced stages.44 The initial screening strategy incorporated serum CA125 as a primary screen with pelvic ultrasound as a second line test to assess ovarian volume and morphology. Using this multimodal screening strategy, a sensitivity at 1 year of 78.6%, a specificity of 99.9% and positive predictive value of 26.8% (approximately four operations for each cancer) for detection of ovarian and fallopian tube cancer was achieved in 22,000 postmenopausal women.45 With the accumulation of data, ovarian morphology instead of volume has been used to refine algorithms for the interpretation of ultrasound.46 Sensitivity has been increased by
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developing a sophisticated statistical (Risk of Ovarian Cancer) algorithm to interpret CA125 levels. This is based on the findings that CA125 levels in women without ovarian cancer are static or decrease with time while levels associated with malignancy tend to rise. The algorithm incorporates age, age specific incidence of ovarian cancer, rate of change and absolute levels of CA125 to calculate an individual’s Risk of Ovarian Cancer. For a target specificity of 98%, the ROC calculation achieved a sensitivity of 86% for preclinical detection of ovarian cancer.47 This approach is part of the screening strategy in the ongoing UK Collaborative Trial of Ovarian Cancer Screening. There are many other tumour markers that are being assessed for screening. These include serum macrophage colony stimulating factor (M-CSF), prostasin, osteopontin, lysophosphatidic acid (LPA), serum inhibin, and human kallikrein especially hK6 and hK10.9,48e50 Recent studies have shown that integrin-linked kinase (irILK) expression, a tumour associated antigen, is present in 6e9-fold higher levels in serum of patients with ovarian cancer compared to the serum of healthy women and those with benign ovarian tumours.51 Surface-enhanced laser desorption ionization time-offlight (SELDI-TOF) and artificial-intelligence-based informatics algorithms have identified a set of key protein values and are able to discriminate normal from ovarian cancer patients. Serum proteomic pattern analysis is being extensively studied in ovarian cancer and might ultimately lead to an ideal marker for screening.9,48e50 Transvaginal scanning Transvaginal scanning is being investigated as both a first line and a second line method in conjunction with CA125 for screening for ovarian cancer.46,52 The transvaginal route is preferred as it gives a more precise image of the ovary. Both ovarian volume and morphology are assessed with cut-offs for volume ranging from 10 ml to 20 ml depending on menopausal status. Persistence of abnormalities on repeat scanning 4e6 weeks following initial detection helps reduce false positive rates. The lack of physiological changes in ovarian volume in postmenopausal women further decreases the number of false positives in this group compared to premenopausal women. However, even in older women there is a high prevalence of benign ovarian lesions. Complex morphology has been used in various screening protocols to assist in reduction of false positives.9e11,53 Both subjective assessment of the grey scale images and weighted scoring systems or morphological indices based on ovarian volume, outline, presence of papillary projections and cyst complexity (i.e. number of locules, wall structure, thickness of septae and echogenecity of fluid) have been explored. Based on gross anatomic changes at the time of surgery, papillary projections have the highest and simple cysts and septal thickness the lowest correlation with a diagnosis of ovarian malignancy.54 There is a definite
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move to manage simple cysts and multilocular cysts conservatively in these apparently healthy postmenopausal women. Numerous studies have looked at whether Doppler will decrease the false positive rates. The rationale is that blood flow patterns are altered in neoplastic tissue and this should assist in their differentiation from physiological and benign conditions of the ovary. Some of these studies have shown that transvaginal ultrasonography is quite precise in distinguishing benign from malignant ovarian tumours and accurately defines the morphological and vascular features of ovarian lesions. However, color flow Doppler findings are not specific enough to be used independent of grey-scale ultrasonography. The specificity does, however, improve significantly with the addition of 3D power Doppler.55,56 Other tests that may be used in distinguishing benign from malignant ovarian lesions are computerized tomography and magnetic resonance imaging. Overall, the data from large prospective studies of screening for ovarian cancer suggest that sequential multimodal screening has superior specificity and positive predictive value compared to strategies based on transvaginal ultrasound alone. However, ultrasound as a first line test may offer greater sensitivity for early stage disease. Target populations and current screening trials A vital part of any screening strategy is identifying the population at risk of developing the disease. The two main populations at increased risk for ovarian cancer are women from the general population aged 50 years or more (90% of the disease occurs in this group) and those aged 35 years or more with a familial risk (based on their family history).57 In both these populations, trials are underway to assess the risks and benefits of screening. In the general population, there are two major randomised controlled trials being undertaken to assess the impact of screening on ovarian cancer mortality. The UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) aims to randomly allocate 200,000 postmenopausal women to a control group (100,000) or screening for 6 years. In the screening arm, two strategies are being tested. Primary screening using CA125 with transvaginal ultrasound as the second line test (multimodal screening, 50,000) or ultrasound screening (50,000).57 The principal end point of the study is death from ovarian cancer. Cost-effectiveness, physical and psychological morbidity, compliance and acceptability of screening are also being studied. Totally 180,000 postmenopausal women have been recruited from 13 centres in the United Kingdom. All participants will be followed up for 7 years via the Office of National Statistics and postal questionnaire. The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial in the United States, has recruited 74,000 women (37,000 in the screen arm and the same number in the nonscreen arm) and will compare a control group with a screened
group undergoing primary screening with both CA125 testing and transvaginal ultrasonography for 3 years followed by CA125 testing alone for a further 2 years. These women will be followed up annually for 13 years following randomisation.58,59 Results of these trials (UKCTOCS in 2012 and PLCO in 2015) should provide information on whether mass screening for ovarian cancer should be implemented. Women were considered at high risk for familial ovarian cancer if they have more than one first-degree relative with ovarian cancer or a combination of early breast and ovarian cancers. Majority of familial ovarian cancer is due to inherited mutations in the BRCA1/BRCA2 breasteovarian cancer susceptibility genes with a small proportion associated with hereditary nonpolyposis colorectal cancer (HNPCC) syndrome. Gene testing is now widely available. However, there are still no definitive answers on how best to manage the ovarian cancer risk in these women. Prophylactic salpingo-oophorectomy has been shown to reduce the risk of ovarian cancer by more than 95% and the breast cancer risk by 50%.57,60,61 Some women, however, would prefer to avoid prophylactic surgery and screening trials are underway in this population. Such trials (UK Familial Ovarian Cancer Screening Study, UKFOCSS, CGN highrisk study and the GOG study in the USA) usually involve screening with CA125 and transvaginal ultrasound in highrisk women over 35 years of age. Many of these women are premenopausal and prone to both physiological and benign conditions that may result in false positive results on ultrasound and CA125 testing. It is important that this population is aware that there is no evidence at present to show that screening can reduce mortality.57 The low prevalence of ovarian cancer means that specificity of the screening strategies must be very high to maintain a reasonable false positive rate. In addition, as women with screen positive results need surgical investigation, the false positive rates of the various strategies available will significantly impact on the overall benefits of ovarian cancer screening.62
Endometrial cancer Endometrial cancer is the most common cancer of the genital tract and represents 10% of all cancers diagnosed in women.63 Most women present with abnormal bleeding in early stage and hence screening for this condition is not currently recommended either in the general population or in women at increased risk due to obesity, infertility or diabetes or use of tamoxifen.64,65 In breast cancer patients on tamoxifen, screening of endometrium using pipelle biopsy has been explored.66 However, further evaluation of routine office endometrial biopsy is required before recommending it as a standard screening test for breast cancer patients on tamoxifen.67,68 Currently, screening is only advocated for women at high risk of the disease due to genetic predisposition
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resulting from hereditary nonpolyposis colorectal cancer (HNPCC) syndrome. The lifetime risk of endometrial cancer in these women can be 40e60%.69,70 These women should be counselled for prophylactic hysterectomy and bilateral salpingo-oophorectomy, if prophylactic colectomy is planned, especially if they have already completed their families. Some studies show that the survival from endometrial cancer in the general population does not significantly differ from women with or at a risk from HNPCC.71 Annual measurement of endometrial thickness using TVS is the most commonly used screening test for this high-risk population. Using a cut-off of 4 mm for endometrial thickness, the sensitivity for detecting endometrial cancer is 98% and the negative predictive value is 99%.9,48e50,72 So far, improved pick up of premalignant and malignant endometrial lesions by Dopplers has not been shown.72 Endometrial pipelle biopsy and hysteroscopy with directed biopsy are used as second line tests. In postmenopausal women, presence of endometrial cells (normal or abnormal) in a Pap smear should raise the suspicion of endometrial cancer.73 However, the test has low sensitivity. K ras mutations have been detected in 10e30% of endometrial cancers on Pap smears from women with these tumours.9,48e50 This raises the possibility of using these and other oncogenes and suppressor genes as markers for detecting endometrial cancers in cervical smears.74 Telomerase expression is noted in a normal menstrual cycle.75 However, activity is either weak or absent in postmenopausal women. As endometrial cancers express telomerase strongly, assay of activity in smears from postmenopausal women has been explored as a screening test for the disease.76
Vulval and vaginal cancer These are rare cancers and sparse literature is available regarding these. Some studies have shown elevation of tissue polypeptide specific antigen (TPS), SCC and urinary core fragment of the beta subunit of HCG. The value of screening has not been explored.43
References 1. What is screening? http://www.nsc.nhs.uk/. 2. Cervical screening has reduced incidence of cancer and mortality. BMJ 1999;318(7188): 0. 3. Sasieni P, Adams J. Effect of screening on cervical cancer mortality in England and Wales: analysis of trends with an age period cohort model. BMJ 1999;318(7193):1244–5. 4. McNeeley Jr SG. New cervical cancer screening techniques. Am J Obstet Gynecol 2003;189(4 Suppl):S40–1. 5. Monsonego J, Autillo-Touati A, Bergeron C, et al. Liquid phase cytology in the primary screening for cervical cancer: a multicenter study. Gynecol Obstet Fertil 2001;29(11):799–807. 6. NICE. Full guidance on the use of liquid-based cytology for cervical screening (review), 2003.
823
7. 2003/54 NICE guidance on liquid based cytology contributes to modernisation of cervical screening services for women. NICE; 2003. 8. Moss S, Gray A, Legood R, Henstock E. First report to the department of health on evaluation of LBC 2002. 9. Menon U, Jacobs IJ. Tumor markers and screening. 4th ed. 2003. 10. Shvartsman HS, Lu KH, Lee J, et al. Overexpression of kallikrein 10 in epithelial ovarian carcinomas. Gynecol Oncol 2003;90(1):44–50. 11. Ni X, Zhang W, Huang KC, et al. Characterisation of human kallikrein 6/protease M expression in ovarian cancer. Br J Cancer 2004;91(4): 725–31. 12. Lorincz AT. Screening for cervical cancer: new alternatives and research. Salud Publica Mex 2003;45(Suppl 3):S376–87. 13. Nieminen P, Vuorma S, Viikki M, Hakama M, Anttila A. Comparison of HPV test versus conventional and automation-assisted Pap screening as potential screening tools for preventing cervical cancer. BJOG 2004;111(8):842–8. 14. Petry KU, Menton S, Menton M, et al. Inclusion of HPV testing in routine cervical cancer screening for women above 29 years in Germany: results for 8466 patients. Br J Cancer 2003;88(10):1570–7. 15. Franco EL. Chapter 13: Primary screening of cervical cancer with human papillomavirus tests. J Natl Cancer Inst Monogr 2003;31:89–96. 16. Cuzick J, Szarewski A, Cubie H, et al. Management of women who test positive for high-risk types of human papillomavirus: the HART study. Lancet 2003;362(9399):1871–6. 17. Cuzick J, Szarewski A, Terry G, et al. Human papillomavirus testing in primary cervical screening. Lancet 1995;345(8964):1533–6. 18. Sasieni PD. Human papillomavirus screening and cervical cancer prevention. J Am Med Womens Assoc 2000;55(4):216–9. 19. Schiffman M, Castle PE. Human papillomavirus: epidemiology and public health. Arch Pathol Lab Med 2003;127(8):930–4. 20. Baay MF, Smits E, Tjalma WA, et al. Can cervical cancer screening be stopped at 50? The prevalence of HPV in elderly women. Int J Cancer 2004;108(2):258–61. 21. Franco EL. Are we ready for a paradigm change in cervical cancer screening? Lancet 2003;362(9399):1866–7. 22. Goldie SJ, Kim JJ, Wright TC. Cost-effectiveness of human papillomavirus DNA testing for cervical cancer screening in women aged 30 years or more. Obstet Gynecol 2004;103(4):619–31. 23. Holmes J, Hemmett L, Garfield S. The cost-effectiveness of human papillomavirus screening for cervical cancer. A review of recent modelling studies. Eur J Health Econ 2005;6(1):30–7. 24. Saslow D, Runowicz CD, Solomon D, et al. American Cancer Society guideline for the early detection of cervical neoplasia and cancer. CA Cancer J Clin 2002;52(6):342–62. 25. Human Papilloma Virus (HPV). http://www.cancerscreening.nhs.uk/ cervical/hpv.html 26. Schiffman M, Solomon D. Findings to date from the ASCUSeLSIL Triage Study (ALTS). Arch Pathol Lab Med 2003;127(8):946–9. 27. Cox JT. The clinician’s view: role of human papillomavirus testing in the American Society for Colposcopy and Cervical Pathology Guidelines for the management of abnormal cervical cytology and cervical cancer precursors. Arch Pathol Lab Med 2003;127(8):950–8. 28. Cuzick J, Sasieni P, Davies P, et al. A systematic review of the role of human papilloma virus (HPV) testing within a cervical screening programme: summary and conclusions. Br J Cancer 2000;83(5):561–5. 29. Almog B, Gamzu R, Bornstein J, et al. Clinical and economic benefit of HPV-load testing in follow-up and management of women postcone biopsy for CIN2-3. Br J Cancer 2003;89(1):109–12. 30. Schiffman M, Khan MJ, Solomon D, et al. A study of the impact of adding HPV types to cervical cancer screening and triage tests. J Natl Cancer Inst 2005;97(2):147–50. 31. Finan RR, Irani-Hakime N, Tamim H, Almawi WY. Validity of vaginal testing in detecting human papillomavirus (HPV) genotypes. J Clin Virol 2000;19(3):163–8. 32. Palmisano ME, Gaffga AM, Daigle J, et al. Detection of human papillomavirus DNA in self-administered vaginal swabs as compared to cervical swabs. Int J STD AIDS 2003;14(8):560–7.
824
A. Sharma, U. Menon / EJSO 32 (2006) 818e824
33. Gravitt PE, Lacey Jr JV, Brinton LA, et al. Evaluation of self-collected cervicovaginal cell samples for human papillomavirus testing by polymerase chain reaction. Cancer Epidemiol Biomarkers Prev 2001; 10(2):95–100. 34. Harper DM, Hildesheim A, Cobb JL, Greenberg M, Vaught J, Lorincz AT. Collection devices for human papillomavirus. J Fam Pract 1999;48(7):531–5. 35. Reddy VG, Khanna N, Jain SK, Das BC, Singh N. Telomerase e a molecular marker for cervical cancer screening. Int J Gynecol Cancer 2001;11(2):100–6. 36. Ngan HY, Cheung AN, Liu SS, Liu KL, Tsao SW. Telomerase assay and HPV 16/18 typing as adjunct to conventional cytological cervical cancer screening. Tumour Biol 2002;23(2):87–92. 37. Wesley R, Sankaranarayanan R, Mathew B, et al. Evaluation of visual inspection as a screening test for cervical cancer. Br J Cancer 1997; 75(3):436–40. 38. Wright Jr TC, Denny L, Kuhn L, Goldie S. Use of visual screening methods for cervical cancer screening. Obstet Gynecol Clin North Am 2002;29(4):701–34. 39. Ferris DG, Payne P, Frisch LE, Milner FH, diPaola FM, Petry LJ. Cervicography: adjunctive cervical cancer screening by primary care clinicians. J Fam Pract 1993;37(2):158–64. 40. Suba EJ, Raab SS. Direct visual inspection for cervical cancer screening. Cancer 2004;101(10):2365 [author reply 2366]. 41. Gaffikin L, Lauterbach M, Blumenthal PD. Performance of visual inspection with acetic acid for cervical cancer screening: a qualitative summary of evidence to date. Obstet Gynecol Surv 2003;58(8): 543–50. 42. Belinson JL, Pretorius RG, Zhang WH, Wu LY, Qiao YL, Elson P. Cervical cancer screening by simple visual inspection after acetic acid. Obstet Gynecol 2001;98(3):441–4. 43. Menon U, Jacobs IJ. Tumor markers. 3rd ed. LWW; 2000. 44. Fritsche HA, Bast RC. CA 125 in ovarian cancer: advances and controversy. Clin Chem 1998;44(7):1379–80. 45. Jacobs I, Davies AP, Bridges J, et al. Prevalence screening for ovarian cancer in postmenopausal women by CA 125 measurement and ultrasonography. BMJ 1993;306(6884):1030–4. 46. Menon U, Talaat A, Rosenthal AN, et al. Performance of ultrasound as a second line test to serum CA125 in ovarian cancer screening. BJOG 2000;107(2):165–9. 47. Skates SJ, Menon U, MacDonald N, et al. Calculation of the risk of ovarian cancer from serial CA-125 values for preclinical detection in postmenopausal women. J Clin Oncol 2003;21(Suppl. 10):206–10. 48. Ardekani AM, Liotta LA, Petricoin 3rd EF. Clinical potential of proteomics in the diagnosis of ovarian cancer. Expert Rev Mol Diagn 2002;2(4):312–20. 49. Bandera CA, Ye B, Mok SC. New technologies for the identification of markers for early detection of ovarian cancer. Curr Opin Obstet Gynecol 2003;15(1):51–5. 50. Markman M, Belinson J, Webster K, et al. Phase 2 trial of interferonbeta as second-line treatment of ovarian cancer, fallopian tube cancer, or primary carcinoma of the peritoneum. Oncology 2004;66(5):343–6. 51. Ahmed N, Oliva K, Rice GE, Quinn MA. Cell-free 59 kDa immunoreactive integrin-linked kinase: a novel marker for ovarian carcinoma. Clin Cancer Res 2004;10(7):2415–20. 52. Chappuis PO, Narod SA, Foulkes WD. Screening for ovarian cancer. Lancet 1999;354(9177):509–10. 53. Diamandis EP, Scorilas A, Fracchioli S, et al. Human kallikrein 6 (hK6): a new potential serum biomarker for diagnosis and prognosis of ovarian carcinoma. J Clin Oncol 2003;21(6):1035–43. 54. Granberg S, Wikland M, Jansson I. Macroscopic characterization of ovarian tumors and the relation to the histological diagnosis: criteria to be used for ultrasound evaluation. Gynecol Oncol 1989;35(2):139–44.
55. Carter JR, Lau M, Fowler JM, Carlson JW, Carson LF, Twiggs LB. Blood flow characteristics of ovarian tumors: implications for ovarian cancer screening. Am J Obstet Gynecol 1995;172(3):901–7. 56. Cohen LS, Escobar PF, Scharm C, Glimco B, Fishman DA. Three-dimensional power Doppler ultrasound improves the diagnostic accuracy for ovarian cancer prediction. Gynecol Oncol 2001;82(1): 40–8. 57. Menon U. Ovarian cancer screening. CMAJ 2004;171(4):323–4. 58. Andriole GL, Reding D, Hayes RB, Prorok PC, Gohagan JK. The prostate, lung, colon, and ovarian (PLCO) cancer screening trial: status and promise. Urol Oncol 2004;22(4):358–61. 59. Hayes RB, Reding D, Kopp W, et al. Etiologic and early marker studies in the prostate, lung, colorectal and ovarian (PLCO) cancer screening trial. Control Clin Trials 2000;21(Suppl. 6):349S–55S. 60. Rebbeck TR. Prophylactic oophorectomy in BRCA1 and BRCA2 mutation carriers. Eur J Cancer 2002;38(Suppl. 6):S15–7. 61. Rebbeck TR, Lynch HT, Neuhausen SL, et al. Prophylactic oophorectomy in carriers of BRCA1 or BRCA2 mutations. N Engl J Med 2002; 346(21):1616–22. 62. Bell R, Petticrew M, Luengo S, Sheldon TA. Screening for ovarian cancer: a systematic review. Health Technol Assess 1998;2(2):i–iv, 1e84. 63. Baiocchi G, Gilardi G. Endometrial carcinoma: an increasing neoplasm. Screening and early diagnosis: proposal for a protocol. Minerva Ginecol 1997;49(4):147–52. 64. Chlebowski RT, Collyar DE, Somerfield MR, Pfister DG. American Society of Clinical Oncology technology assessment on breast cancer risk reduction strategies: tamoxifen and raloxifene. J Clin Oncol 1999; 17(6):1939–55. 65. ACOG committee opinion: tamoxifen and endometrial cancer. Int J Gynaecol Obstet 2001;73(1):77–9. 66. Berliere M, Charles A, Galant C, Donnez J. Uterine side effects of tamoxifen: a need for systematic pretreatment screening. Obstet Gynecol 1998;91(1):40–4. 67. Barakat RR. Benign and hyperplastic endometrial changes associated with tamoxifen use. Oncology (Huntingt) 1997;11(2 Suppl. 1):35–7. 68. Barakat RR. Screening for endometrial cancer in the patient receiving tamoxifen for breast cancer. J Clin Oncol 1999;17(7):1967–8. 69. Huang D, Chen C, Sun W, Strom CM, Bender RA. High-throughput gene sequencing assay development for hereditary nonpolyposis colon cancer. Clin Colorectal Cancer 2004;4(4):275–9. 70. Chung L, Broaddus R, Crozier M, Luthraa R, Levenback C, Lu K. Unexpected endometrial cancer at prophylactic hysterectomy in a woman with hereditary nonpolyposis colon cancer. Obstet Gynecol 2003; 102(5 Pt 2):1152–5. 71. Boks DE, Trujillo AP, Voogd AC, Morreau H, Kenter GG, Vasen HF. Survival analysis of endometrial carcinoma associated with hereditary nonpolyposis colorectal cancer. Int J Cancer 2002;102(2):198–200. 72. Barik S, Tidy J. Screening for endometrial cancer in asymptomatic postmenopausal women with conventional and colour Doppler sonography. Br J Obstet Gynaecol 1999;106(11):1229–30. 73. Zygmunt A, Markowska J, Fischer N. Significance of tissue polypeptide specific antigen (TPS) in diagnosis and monitoring of treatment in ovarian cancer. Eur J Gynaecol Oncol 1998;19(5):484–6. 74. Al-Jehani RM, Jeyarajah AR, Hagen B, Hogdall EV, Oram DH, Jacobs IJ. Model for the molecular genetic diagnosis of endometrial cancer using K-ras mutation analysis. J Natl Cancer Inst 1998;90(7): 540–2. 75. Yokoyama Y, Takahashi Y, Morishita S, Hashimoto M, Niwa K, Tamaya T. Telomerase activity in the human endometrium throughout the menstrual cycle. Mol Hum Reprod 1998;4(2):173–7. 76. Zheng PS, Iwasaka T, Yamasaki F, et al. Telomerase activity in gynecologic tumors. Gynecol Oncol 1997;64(1):171–5.