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The prevalence of non-sentinel node metastases in breast cancer patients with sentinel node micrometastases
EJSO (2005) 31, 13–18
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The prevalence of non-sentinel node metastases in breast cancer patients with sentinel node micrometastases ¨c, L.A. Krogerusd, M.H.K. Leideniusa,*, J.H. Vironenb, M.S. Riihela ¨d T.S. Toivonend, K.A.J. von Smittena, P.S. Heikkila a
Breast Surgery Unit, Maria Hospital, Lapinlahdenkatu 16, FIN-00180 Helsinki, Finland Breast Surgery Unit, Jorvi Hospital, Espoo, Finland c Department of Pathology, Jorvi Hospital, Espoo, Finland d Department of Pathology, Helsinki University Hospital, Helsinki, Finland b
Accepted for publication 6 September 2004 Available online 30 November 2004
KEYWORDS Axillary clearance; Breast cancer; Micrometastases; Sentinel node
Abstract Aims. The aim of the study was to estimate the prevalence of and risk factors for non-sentinel node (NSN) involvement in breast cancer patients with sentinel node (SN) micrometastases. Methods. Eighty-four patients with SN micrometastases were included. Both the SN and NSN were examined using serial sectioning and immunohistohemistry. Various indices were evaluated as possible risk factors for NSN involvement. Results. NSN involvement was found in 22/84 patients. The median size of the NSN metastases was 1.25 mm (0.01–12 mm). The NSN metastases were larger than 2 mm in 8 patients and smaller than 0.2 mm in 6 patients. NSN involvement was observed in 14/35 patients with metastatic findings in all removed SN. Three of the 23 patients with 2 or 3 tumour negative SN had NSN metastases. None of the 12 patients with 4 or more uninvolved SN had NSN metastases. NSN involvement could not excluded by other patient, tumour or sentinel node related factors. Conclusions. Every fourth patient will have residual disease in the axilla, 10% even large metastases, if axillary clearance is omitted in patients with SN micrometastases. The risk of NSN involvement seems negligible in patients with a single SN micrometastasis and four or more healthy SN harvested. q 2004 Elsevier Ltd. All rights reserved.
Introduction * Corresponding author. Tel.: C358 50 4271005; fax: C358 9 47163490. E-mail address: [email protected] (M.H.K. Leidenius).
The sentinel nodes (SN) are the only tumour positive nodes in more than half of breast cancer patients
0748-7983/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejso.2004.09.012
14 with SN metastases.1–11 The most powerful predictors for non-sentinel node (NSN) involvement are the size and the extra nodal extension of the SN metastasis, the presence of multiple SN metastases as well as the size and lymphovascular invasion of the primary tumour.12 Attempts have been made to identify a subgroup of patients with a very low probability of NSN involvement in whom axillary clearance (AC) could be omitted despite tumour positive SN findings. The focus has been on patients with small primary tumours and SN micrometastases, metastases not larger than 2 mm. Moreover, the intraoperative histological assessment of SN micrometastases frequently fails,13 leading to AC as a second operation. These second operations increase not only hospital costs,14 but also patient distress. The prevalence of NSN involvement in patients with SN micrometastases has varied ranging from 0 to 34%.1–11,15,16 The widely varying prevalence of NSN involvement is probably due to small study populations and differences in the histological examination of SN and NSN. The aim of this study was to estimate the prevalence of and risk factors for NSN involvement in breast cancer patients with SN micrometastases. Special attention was paid to identification of a subgroup of patients who could avoid AC as a second operation after a false negative intraoperative diagnosis of SN micrometastases.
Patients and methods The prospective, cross-sectional study was carried out between November 2002 and October 2003 at the Breast Surgery Units of Maria Hospital and Jorvi Hospital, Helsinki University Hospital. During the study period, SN micrometastases were detected in altogether 105 breast cancer patients, either in the frozen section (50 patients) or in the postoperative histological diagnosis. The project plan was approved by the Ethical Committee of Helsinki City University Hospitals. Written informed consent was obtained from each patient. We failed to include 3 patients in the study. Their AC specimens were assessed routinely, not using serial sectioning and immunohistochemistry (IHC). No NSN metastases were detected in these 3 patients. AC was not performed in 6 patients, who were also excluded. Twelve of the 50 patients with micrometastases in the frozen section, had larger metastases in the postoperative diagnosis and were analysed as a separate group. The characteristics of
M.H.K. Leidenius et al. the remaining 84 study patients are presented in Table 1.
Surgery Preoperative lymphatic mapping, a handheld gamma detector and blue dye were used to identify the sentinel nodes in the axilla. Lymphoscintigraphy was performed the day before surgery a median of 4 h after a single intratumoral injection of 100 MBq of 99mTc labelled human albumin colloid Nanocollw (Nycomed Amersham Sorin s.r.l. Saluggia, Italy), with particle size less than 80 nm in a volume of 0.2 ml. At least 5 min before incision, 1 ml of patent blue dye was injected intra tumorally (Bleu Patente ´ V; Laboratoire Geuerbet, Aulnay-sous-Bois, France). All focally radioactive and/or blue nodes in the axilla were harvested. Level I–II AC was performed during the primary operation in patients with SN metastases in the frozen section as well as in 1 patient, who insisted AC regardless the result of SN biopsy. Patients with false negative findings in the frozen section diagnosis underwent level I–II AC as a second operation. Table 1 The characteristics of the 84 breast cancer patients with sentinel node micrometastases Age (years)a Histological tumour size (mm)a Histological tumour stage T1 T2 T4 Tumour location Upper lateral Lower lateral Upper medial Lower medial Central Tumour histology Invasive ductal Invasive lobular Invasive other types Tumour grade I II III Not applicable Lymphovascular invasion Present Absent Not determined a
Median (range).
55 (30–85) 15 (2–40)
65 18 1 40 14 14 5 11 55 18 11 24 42 17 1 34 41 9
Prevalence of non-sentinel node metastases
15
Histology
Results
The SN were sent to the pathology laboratory as separate samples. The fresh specimens were cleaned from all extracapsular fat tissue, measured, sliced into 1–1.5 mm thick sections perpendicular to their long axis and arranged on pre-frozen Tissue-Tekw OCTe-compound. Touch preparations from the surface and frozen sections from two levels were made from these slices; these were then stained with toluidine blue and viewed. In 46 cases, rapid intraoperative IHC was also used, either Cam 5.2 or a quicker method with Cytonel Ultrapid IHC (Immuno Diagnostics Oy, Ha ¨meenlinna, Finland). Malignancy was reported to the operating room as soon as it was detected. The remaining tissue was fixed in formalin and embedded in paraffin. Two sections were stained with H & E. When a metastasis of 2 mm or larger was found in the frozen section procedure, only H & E sections were made from paraffin embedded tissue. If no metastatic tissue was detected or only isolated tumour cells or a micrometastasis was found, a Cam 5.2 immunostain (Becton Dickinson Immunocytometry Systems, San Jose, Ca, USA) was performed on paraffin embedded tissue in addition to the regular H & E sections. Metastases of 2 mm or less were considered to be micrometastases. When a metastasis was found in a frozen section, the remaining nodes were stained with H & E and Cam 5.2. Lymph-nodes were identified from the formalin fixed AC specimens. Each node was sliced into 1 mm thick sections and embedded in paraffin. Thereafter, H & E and Cam 5.2 stained sections were cut from two levels (approximately 300 mm apart). In patients with AC as a second operation, the scar tissue after SN biopsy was processed for microscopical analysis in two perpendicular planes.
The median number of harvested SN was 2 (1–11) and the median total number of examined axillary nodes was 19 (8–34). The median number of uninvolved SN was 1 (1–10) and the median number of tumour positive SN was 1 (1–3). The SN micrometastasis was detected in frozen section in 38/84 patients and by IHC only in 23/84 patients. The median size of the SN metastasis was 0.4 mm (0.05– 2 mm) (Table 2). NSN involvement was found in 22/84 patients with a median of 1 NSN metastasis. The median size of the NSN metastases was 1.25 mm (0.01–12 mm). The NSN metastases were larger than 2 mm in 8 patients and smaller than 0.2 mm in 6 patients (Table 2). The median number of examined NSN was 15 (10– 25) in patients with NSN involvement and 17 (6– 27) in patients without NSN involvement (pZns). The prevalence of NSN involvement increased with increasing number micrometastatic SN. NSN metastases were detected in 15 of the 74 patients with one involved SN, in 5 of the 8 patients with two involved SN and in both of the 2 patients with 3 metastatic nodes (pZ0.02) Table 3. NSN involvement was observed in 14/35 patients with metastatic findings in all removed SN and in 5/14 patients who had one uninvolved SN removed in addition to the tumour positive ones. Three of the 23 patients with 2 or 3 tumour negative SN had NSN metastases. None of the 12 patients with 4 or more uninvolved SN had NSN metastases (p!0.05) (Table 3). We were not able to exclude NSN involvement by other patient, tumour or sentinel node related factors. However, NSN metastases were more Table 2 The characteristics of the sentinel node (SN) micrometastases in the 84 breast cancer patients
Statistical methods
Intraoperative frozen section diagnosis
The number of removed involved and uninvolved SN, the number of examined NSN, the size, the number and the detection method of the SN metastases, the location, the histological type, the grade, the size, the stage and lymphovascular invasion of the primary tumour and the age of the patient were evaluated as possible risk factors for NSN involvement. Proportional data was compared using two-sided chi-square or Fisher exact tests. The medians were compared using the Mann– Whitney U-test. Two-tailed p-values !0.05 were considered statistically significant.
False negative 45 True positive 38 Not applied 1 Detectable by IHC only 23 The size of the micrometastasis 1–2 mm 27 0.2–1 mm 33 !0.2 mm 24 The size of the micro0.4 (0.05–2) metastasis (mm)a IHC, immunohistochemistry. a Median (range).
Patients
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M.H.K. Leidenius et al.
Table 3 The influence of tumour and sentinel node related factors on the prevalence of non-sentinel node metastases in 84 patients breast cancer patients with sentinel node micrometastases The prevalence of non-sentinel node metastases All patients (NZ84) Patients with false negative frozen section diagnosis (NZ45) Histological tumour stage T1a–b 8/20 T1 c 7/45 T2 or larger 7/19 Tumour location Lateral 16/54 Mediocentral 6/30 Tumour histology Invasive ductal 17/55 Invasive lobular 4/18 Invasive other 1/11 Tumour grade I 5/24 II 12/42 III 5/17 Lymphovascular invasiona Present 16/34 Absent 6/41 Micrometastasis detected by H&E 16/61 IHC only 6/23 The size of the micrometastasis 1–2 mm 10/27 0.2–1 mm 7/33 !0.2 mm 5/19
5/12 2/24 1/9 6/25 2/20 6/30 2/10 0/5 4/15 2/20 2/9 5/13 3/28 2/23 6/22 2/8 3/17 3/20
H & E, haematoxylin and eosin; IHC, immunohistochemistry. a pZ0.02 among all patients and p!0.05 among those with false negative frozen section diagnosis.
common, in 16/34 patients, in connection with lymphovascular invasion compared with the 6/41 encountered when lymphovascular invasion was absent (pZ0.02). NSN involvement also seemed less common, in 8/45 patients with false negative results in the frozen section, than in 14/38 patients with their micrometastases detected already intra operatively, but the difference was not statistically significant (Table 3).
The intraoperative evaluation of the size of the SN metastasis Altogether 50 patients in the entire study population had micrometastatic findings in the intraoperative diagnosis, but the SN metastasis was larger than 2 mm in 12 of them. The median size of the metastasis was 2.75 mm (2.1–7 mm) in these 12 patients. NSN involvement was found in 4/12 patients.
NSN involvement in patients with false negative findings in the frozen section
Discussion NSN metastases were observed in 8 patients of the 45 with micrometastases undetected in the frozen section. The NSN metastases were larger than 2 mm in 4 patients. Sixteen patients in this subgroup had three or more uninvolved SN harvested in addition to the micrometastatic ones. None of them had NSN involvement (p!0.05). NSN involvement could not excluded by other patient, tumour or sentinel node related factors in this subgroup (Table 3).
The prevalence of NSN metastases The use of IHC facilitates the detection of metastases in the AC specimen.9 The prevalence of NSN involvement in patients with SN micrometastases may be underestimated even when examining the NSN with serial sectioning and IHC. Patients with SN micrometatases often undergo AC as a second
Prevalence of non-sentinel node metastases operation a couple of weeks after SNB, because of frequently failing intraoperative diagnosis of SN micrometastases. Consequently, scar tissue in the lower part of the axilla makes the histological evaluation of the AC specimen difficult. Our pathologists (PH and MR) found no lymph-nodes among the scar tissue in the AC specimens. In the present and the previous studies, large NSN metastases have been found in 8–16% of patients with SN micrometastases only.3,15 The size of the SN metastasis may be underestimated and the so called micrometastasis may represent only a part of a larger one. Another possible explanation is that the real SN with a large metastasis has not been identified, because of total or partial diversion of the lymphatic drainage from the original SN to a lesser involved one. Accordingly, the false negative rate in SN biopsy has been clearly lower when using serial sectioning and IHC in the examination of the SN.17
Risk factors for NSN metastases Risk factors for NSN involvement have been studied widely with the results summarised in a recent meta-analysis.12 The majority of previous studies have included all patients with SN metastases and the number of patients with SN micrometastases has been small. In the present study, the numbers of involved and uninvolved SN were the factors predicting NSN metastases. The numbers of involved and uninvolved SN were independent risk factors for NSN metastases also in the study by van Zee and co workers, who did not include the size of the metastasis in their analysis.18 NSN metastases seemed more common in patients with micrometastases detected already in the frozen section or when the size of the micrometatastasis was at least 1 mm, but the findings were not statistically significant. The latter finding is in agreement with an observation in a previous study stating the risk of NSN involvement in patients with micrometastases larger than 1 mm to be equal to that encountered in connection with SN macrometastases.15
The influence of the lymphatic mapping and the histological methods The likelihood of detecting SN micrometastases is correlated with the number of sections examined and the sectioning interval.15 If the SN metastasis is detected already in the intraoperative diagnosis, in the postoperative evaluation with H & E staining or
17 by IHC only is depending on the methods used in the assessment of SN metastases. The smallest micrometastases may remain undetected by the pathologist.19 Also the size of the metastasis may be underestimated, especially in the frozen section. In the present study, the SN micrometastasis detected in the frozen section proved to be a large one in almost every fourth patient. The lymphatic mapping methods, like the injection site, the dose, the volume and the particle size of the radioactive tracer, vary between the units leading to different numbers of axillary nodes removed as SN. Because a standard in the identification as well as in the histological examination of the SN is lacking, clinical decision making should not be based only on the observations made in other units. Furthermore, we recommend AC in all patients with SN metastases in the frozen section, because the size of the SN metastasis, the number of involved and uninvolved SN as well as the features of the primary tumour are not exactly known before the postoperative histopathological examination of the specimens.
The role of AC The advantage of AC in patients with tumour positive SN has been questioned.20 The risk of clinically manifest axillary recurrence seems to be negligible after omitting AC in patients with SN micrometastases, at least during a short followup.20 Furthermore, the NSABP B-04 study concluded no survival advantage of a prophylactic AC in clinically node negative patients.21 On the other hand, AC is proposed to provide not only excellent regional control but also a survival benefit independent of systemic adjuvant therapy.22–24 Abandoning axillary clearance in patients with SN metastases outside prospective trials is not advisable. However, omitting AC as second operation can be considered in patients with a single SN micrometatasis and several uninvolved SN and of course in patients with severe comorbidity.
Conclusions Every fourth patient will have residual disease in the axilla, 10% even large metastases, if AC is omitted in patients with SN micrometastases. The risk of NSN involvement seems negligible in patients with a single SN micrometastasis and several healthy SN harvested.
18
M.H.K. Leidenius et al.
Acknowledgements The study was supported by a grant from Helsinki University Hospital Research Fund.
12.
13.
References 1. Chu KU, Turner RR, Hansen NM, Brennan MB, Giuliano AE. Sentinel node metastasis in patients with breast carcinoma accurately predicts immunohistochemically detectable nonsentinel node metastases. Ann Surg Oncol 1999;6:756–61. 2. Weiser MR, Montgomery LL, Tan LK, et al. Lymphovascular invasion enhances the prediction of non-sentinel node metastases in breast cancer patients with positive sentinel nodes. Ann Surg Oncol 2001;8:145–9. 3. Turner RR, Chu KU, Qi K, et al. Pathologic features associated with nonsentinel lymph node metastases in patients with metastatic breast carcinoma in a sentinel lymph node. Cancer 2000;89:574–81. 4. Mignonette H, Treilleux I, Faure C, Nessah K, Bredmond A. Axillary lymph-node dissection for positive sentinel lymph nodes in breast cancer patients. Eur J Surg Oncol 2002;28: 623–6. 5. Hwang RF, Krishnamurty S, Hunt KK, et al. Clinicopathologic factors predeicting involvement of nonsentinel axillary nodes in women with breast cancer. Ann Surg Oncol 2003; 10:248–54. 6. Nos C, Harding-MacKean C, Fre ´neaux P, et al. Prediction of tumour involvement in remaining axillary nodes when the sentinel node in a woman with breast cancer contains metastases. Br J Surg 2003;90:1354–60. 7. Liang WC, Sickle-Santanello BJ, Nims TA. Is a completion axillary dissection indicated for micrometastases in the sentinel lymph node? Am J Surg 2001;182:365–8. 8. van Iterson V, Leidenius M, Krogerus L, von Smitten K. Predictive factors for the status of nonsentinel nodes in breast cancer patients with tumor positive sentinel nodes. Breast Cancer Res Treat 2003;82:39–45. 9. Reynolds C, Mick R, Donohue JH, et al. Sentinel lymph node biopsy with metastasis: can axillary dissection be avoided in some patients with breast cancer? J Clin Oncol 1999;17: 1720–6. 10. Abdessalam SF, Zervos EE, Prasad M, et al. Predictors of positive axillary lymph nodes after sentinel lymph node biopsy in breast cancer. Am J Surg 2001;182:316–20. 11. Kamath VJ, Giuliano R, Dauway EL, et al. Characteristics of
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the sentinel lymph node in breast cancer predict further involvement of higher-echelon nodes in the axilla. Arch Surg 2001;136:688–92. Degnim AC, Griffith KA, Sabel MS, et al. Clinicopathologic features of metastasis in nonsentinel lymph nodes of breast carcinoma patients. Cancer 2003;98:2307–15. Leidenius MHKL, Krogerus LA, Toivonen TS, von Smitten KAV. The feasibility of intraoperative diagnosis of sentinel lymph node metastases in breast cancer. J Surg Oncol 2003;84: 68–73. Ro ¨nka ¨ R, von Smitten K, Sintonen H, et al. The impact of sentinel node biopsy and axillary staging strategy on hospital costs. Ann Oncol 2004;15:88–94. Viale G, Maiorano E, Mazzarol G, et al. Histologic detection and clinical implications of micrometastases in axillary sentinel lymph nodes for patients with breast carcinoma. Cancer 2001;92:1378–84. den Bakker MA, van Weeszenberg A, de Kanter AY, et al. Non-sentinel lymph node involvement in patients with breast cancer and sentinel node micrometastasis; too early to abandon axillary clearance. J Clin Pathol 2002;5:932–5. Liberman L. Pathologic analysis of sentinel lymph nodes in breast cancer. Cancer 2000;88:971–7. van Zee KJ, Manasseh D-ME, Bevilacqua JL, et al. A nomogram for predicting the likelihood of additional nodal metastases in breast cancer patients with a positive sentinel node biopsy. Ann Surg Oncol 2003;10:1140–51. Roberts CA, Beitsch PD, Litz CE, et al. Interpretive disparity among pathologists in breast sentinel lymph node evaluation. Am J Surg 2003;186:324–9. Guenther JM, Hansen NM, DiFronzo LA, et al. Axillary dissection is not required for all patients with breast cancer and positive sentinel nodes. Arch Surg 2003;138:52–6. Fisher B, Redmond C, Fisher ER, et al. Ten-year result of a randomized clinical trial comparing radical mastectomy and total mastectomy with or without radiation. N Engl J Med 1985;312:674–81. Orr RK. The impact of prophylactic axillary node dissection on breast cancer survival—a Bayesian meta-analysis. Ann Surg Oncol 1999;6:109–16. Axelsson CK, Rank F, Blichert-Toft M, Mouridsen HT, Jensen M-B. Impact of axillary dissection on staging and regional control in breast tumor !10 mm. The DBCG experience. Acta Oncol 2000;39:283–9. Bland KI, Scott-Conner CEH, Menck H, Winchester DP. Axillary dissection in breast-conserving surgery for stage I and II breast cancer: a national cancer data base study of patterns of omission and implications for survival. J Am Coll Surg 1999;188:586–96.
www.ejso.com
The prevalence of non-sentinel node metastases in breast cancer patients with sentinel node micrometastases ¨c, L.A. Krogerusd, M.H.K. Leideniusa,*, J.H. Vironenb, M.S. Riihela ¨d T.S. Toivonend, K.A.J. von Smittena, P.S. Heikkila a
Breast Surgery Unit, Maria Hospital, Lapinlahdenkatu 16, FIN-00180 Helsinki, Finland Breast Surgery Unit, Jorvi Hospital, Espoo, Finland c Department of Pathology, Jorvi Hospital, Espoo, Finland d Department of Pathology, Helsinki University Hospital, Helsinki, Finland b
Accepted for publication 6 September 2004 Available online 30 November 2004
KEYWORDS Axillary clearance; Breast cancer; Micrometastases; Sentinel node
Abstract Aims. The aim of the study was to estimate the prevalence of and risk factors for non-sentinel node (NSN) involvement in breast cancer patients with sentinel node (SN) micrometastases. Methods. Eighty-four patients with SN micrometastases were included. Both the SN and NSN were examined using serial sectioning and immunohistohemistry. Various indices were evaluated as possible risk factors for NSN involvement. Results. NSN involvement was found in 22/84 patients. The median size of the NSN metastases was 1.25 mm (0.01–12 mm). The NSN metastases were larger than 2 mm in 8 patients and smaller than 0.2 mm in 6 patients. NSN involvement was observed in 14/35 patients with metastatic findings in all removed SN. Three of the 23 patients with 2 or 3 tumour negative SN had NSN metastases. None of the 12 patients with 4 or more uninvolved SN had NSN metastases. NSN involvement could not excluded by other patient, tumour or sentinel node related factors. Conclusions. Every fourth patient will have residual disease in the axilla, 10% even large metastases, if axillary clearance is omitted in patients with SN micrometastases. The risk of NSN involvement seems negligible in patients with a single SN micrometastasis and four or more healthy SN harvested. q 2004 Elsevier Ltd. All rights reserved.
Introduction * Corresponding author. Tel.: C358 50 4271005; fax: C358 9 47163490. E-mail address: [email protected] (M.H.K. Leidenius).
The sentinel nodes (SN) are the only tumour positive nodes in more than half of breast cancer patients
0748-7983/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.ejso.2004.09.012
14 with SN metastases.1–11 The most powerful predictors for non-sentinel node (NSN) involvement are the size and the extra nodal extension of the SN metastasis, the presence of multiple SN metastases as well as the size and lymphovascular invasion of the primary tumour.12 Attempts have been made to identify a subgroup of patients with a very low probability of NSN involvement in whom axillary clearance (AC) could be omitted despite tumour positive SN findings. The focus has been on patients with small primary tumours and SN micrometastases, metastases not larger than 2 mm. Moreover, the intraoperative histological assessment of SN micrometastases frequently fails,13 leading to AC as a second operation. These second operations increase not only hospital costs,14 but also patient distress. The prevalence of NSN involvement in patients with SN micrometastases has varied ranging from 0 to 34%.1–11,15,16 The widely varying prevalence of NSN involvement is probably due to small study populations and differences in the histological examination of SN and NSN. The aim of this study was to estimate the prevalence of and risk factors for NSN involvement in breast cancer patients with SN micrometastases. Special attention was paid to identification of a subgroup of patients who could avoid AC as a second operation after a false negative intraoperative diagnosis of SN micrometastases.
Patients and methods The prospective, cross-sectional study was carried out between November 2002 and October 2003 at the Breast Surgery Units of Maria Hospital and Jorvi Hospital, Helsinki University Hospital. During the study period, SN micrometastases were detected in altogether 105 breast cancer patients, either in the frozen section (50 patients) or in the postoperative histological diagnosis. The project plan was approved by the Ethical Committee of Helsinki City University Hospitals. Written informed consent was obtained from each patient. We failed to include 3 patients in the study. Their AC specimens were assessed routinely, not using serial sectioning and immunohistochemistry (IHC). No NSN metastases were detected in these 3 patients. AC was not performed in 6 patients, who were also excluded. Twelve of the 50 patients with micrometastases in the frozen section, had larger metastases in the postoperative diagnosis and were analysed as a separate group. The characteristics of
M.H.K. Leidenius et al. the remaining 84 study patients are presented in Table 1.
Surgery Preoperative lymphatic mapping, a handheld gamma detector and blue dye were used to identify the sentinel nodes in the axilla. Lymphoscintigraphy was performed the day before surgery a median of 4 h after a single intratumoral injection of 100 MBq of 99mTc labelled human albumin colloid Nanocollw (Nycomed Amersham Sorin s.r.l. Saluggia, Italy), with particle size less than 80 nm in a volume of 0.2 ml. At least 5 min before incision, 1 ml of patent blue dye was injected intra tumorally (Bleu Patente ´ V; Laboratoire Geuerbet, Aulnay-sous-Bois, France). All focally radioactive and/or blue nodes in the axilla were harvested. Level I–II AC was performed during the primary operation in patients with SN metastases in the frozen section as well as in 1 patient, who insisted AC regardless the result of SN biopsy. Patients with false negative findings in the frozen section diagnosis underwent level I–II AC as a second operation. Table 1 The characteristics of the 84 breast cancer patients with sentinel node micrometastases Age (years)a Histological tumour size (mm)a Histological tumour stage T1 T2 T4 Tumour location Upper lateral Lower lateral Upper medial Lower medial Central Tumour histology Invasive ductal Invasive lobular Invasive other types Tumour grade I II III Not applicable Lymphovascular invasion Present Absent Not determined a
Median (range).
55 (30–85) 15 (2–40)
65 18 1 40 14 14 5 11 55 18 11 24 42 17 1 34 41 9
Prevalence of non-sentinel node metastases
15
Histology
Results
The SN were sent to the pathology laboratory as separate samples. The fresh specimens were cleaned from all extracapsular fat tissue, measured, sliced into 1–1.5 mm thick sections perpendicular to their long axis and arranged on pre-frozen Tissue-Tekw OCTe-compound. Touch preparations from the surface and frozen sections from two levels were made from these slices; these were then stained with toluidine blue and viewed. In 46 cases, rapid intraoperative IHC was also used, either Cam 5.2 or a quicker method with Cytonel Ultrapid IHC (Immuno Diagnostics Oy, Ha ¨meenlinna, Finland). Malignancy was reported to the operating room as soon as it was detected. The remaining tissue was fixed in formalin and embedded in paraffin. Two sections were stained with H & E. When a metastasis of 2 mm or larger was found in the frozen section procedure, only H & E sections were made from paraffin embedded tissue. If no metastatic tissue was detected or only isolated tumour cells or a micrometastasis was found, a Cam 5.2 immunostain (Becton Dickinson Immunocytometry Systems, San Jose, Ca, USA) was performed on paraffin embedded tissue in addition to the regular H & E sections. Metastases of 2 mm or less were considered to be micrometastases. When a metastasis was found in a frozen section, the remaining nodes were stained with H & E and Cam 5.2. Lymph-nodes were identified from the formalin fixed AC specimens. Each node was sliced into 1 mm thick sections and embedded in paraffin. Thereafter, H & E and Cam 5.2 stained sections were cut from two levels (approximately 300 mm apart). In patients with AC as a second operation, the scar tissue after SN biopsy was processed for microscopical analysis in two perpendicular planes.
The median number of harvested SN was 2 (1–11) and the median total number of examined axillary nodes was 19 (8–34). The median number of uninvolved SN was 1 (1–10) and the median number of tumour positive SN was 1 (1–3). The SN micrometastasis was detected in frozen section in 38/84 patients and by IHC only in 23/84 patients. The median size of the SN metastasis was 0.4 mm (0.05– 2 mm) (Table 2). NSN involvement was found in 22/84 patients with a median of 1 NSN metastasis. The median size of the NSN metastases was 1.25 mm (0.01–12 mm). The NSN metastases were larger than 2 mm in 8 patients and smaller than 0.2 mm in 6 patients (Table 2). The median number of examined NSN was 15 (10– 25) in patients with NSN involvement and 17 (6– 27) in patients without NSN involvement (pZns). The prevalence of NSN involvement increased with increasing number micrometastatic SN. NSN metastases were detected in 15 of the 74 patients with one involved SN, in 5 of the 8 patients with two involved SN and in both of the 2 patients with 3 metastatic nodes (pZ0.02) Table 3. NSN involvement was observed in 14/35 patients with metastatic findings in all removed SN and in 5/14 patients who had one uninvolved SN removed in addition to the tumour positive ones. Three of the 23 patients with 2 or 3 tumour negative SN had NSN metastases. None of the 12 patients with 4 or more uninvolved SN had NSN metastases (p!0.05) (Table 3). We were not able to exclude NSN involvement by other patient, tumour or sentinel node related factors. However, NSN metastases were more Table 2 The characteristics of the sentinel node (SN) micrometastases in the 84 breast cancer patients
Statistical methods
Intraoperative frozen section diagnosis
The number of removed involved and uninvolved SN, the number of examined NSN, the size, the number and the detection method of the SN metastases, the location, the histological type, the grade, the size, the stage and lymphovascular invasion of the primary tumour and the age of the patient were evaluated as possible risk factors for NSN involvement. Proportional data was compared using two-sided chi-square or Fisher exact tests. The medians were compared using the Mann– Whitney U-test. Two-tailed p-values !0.05 were considered statistically significant.
False negative 45 True positive 38 Not applied 1 Detectable by IHC only 23 The size of the micrometastasis 1–2 mm 27 0.2–1 mm 33 !0.2 mm 24 The size of the micro0.4 (0.05–2) metastasis (mm)a IHC, immunohistochemistry. a Median (range).
Patients
16
M.H.K. Leidenius et al.
Table 3 The influence of tumour and sentinel node related factors on the prevalence of non-sentinel node metastases in 84 patients breast cancer patients with sentinel node micrometastases The prevalence of non-sentinel node metastases All patients (NZ84) Patients with false negative frozen section diagnosis (NZ45) Histological tumour stage T1a–b 8/20 T1 c 7/45 T2 or larger 7/19 Tumour location Lateral 16/54 Mediocentral 6/30 Tumour histology Invasive ductal 17/55 Invasive lobular 4/18 Invasive other 1/11 Tumour grade I 5/24 II 12/42 III 5/17 Lymphovascular invasiona Present 16/34 Absent 6/41 Micrometastasis detected by H&E 16/61 IHC only 6/23 The size of the micrometastasis 1–2 mm 10/27 0.2–1 mm 7/33 !0.2 mm 5/19
5/12 2/24 1/9 6/25 2/20 6/30 2/10 0/5 4/15 2/20 2/9 5/13 3/28 2/23 6/22 2/8 3/17 3/20
H & E, haematoxylin and eosin; IHC, immunohistochemistry. a pZ0.02 among all patients and p!0.05 among those with false negative frozen section diagnosis.
common, in 16/34 patients, in connection with lymphovascular invasion compared with the 6/41 encountered when lymphovascular invasion was absent (pZ0.02). NSN involvement also seemed less common, in 8/45 patients with false negative results in the frozen section, than in 14/38 patients with their micrometastases detected already intra operatively, but the difference was not statistically significant (Table 3).
The intraoperative evaluation of the size of the SN metastasis Altogether 50 patients in the entire study population had micrometastatic findings in the intraoperative diagnosis, but the SN metastasis was larger than 2 mm in 12 of them. The median size of the metastasis was 2.75 mm (2.1–7 mm) in these 12 patients. NSN involvement was found in 4/12 patients.
NSN involvement in patients with false negative findings in the frozen section
Discussion NSN metastases were observed in 8 patients of the 45 with micrometastases undetected in the frozen section. The NSN metastases were larger than 2 mm in 4 patients. Sixteen patients in this subgroup had three or more uninvolved SN harvested in addition to the micrometastatic ones. None of them had NSN involvement (p!0.05). NSN involvement could not excluded by other patient, tumour or sentinel node related factors in this subgroup (Table 3).
The prevalence of NSN metastases The use of IHC facilitates the detection of metastases in the AC specimen.9 The prevalence of NSN involvement in patients with SN micrometastases may be underestimated even when examining the NSN with serial sectioning and IHC. Patients with SN micrometatases often undergo AC as a second
Prevalence of non-sentinel node metastases operation a couple of weeks after SNB, because of frequently failing intraoperative diagnosis of SN micrometastases. Consequently, scar tissue in the lower part of the axilla makes the histological evaluation of the AC specimen difficult. Our pathologists (PH and MR) found no lymph-nodes among the scar tissue in the AC specimens. In the present and the previous studies, large NSN metastases have been found in 8–16% of patients with SN micrometastases only.3,15 The size of the SN metastasis may be underestimated and the so called micrometastasis may represent only a part of a larger one. Another possible explanation is that the real SN with a large metastasis has not been identified, because of total or partial diversion of the lymphatic drainage from the original SN to a lesser involved one. Accordingly, the false negative rate in SN biopsy has been clearly lower when using serial sectioning and IHC in the examination of the SN.17
Risk factors for NSN metastases Risk factors for NSN involvement have been studied widely with the results summarised in a recent meta-analysis.12 The majority of previous studies have included all patients with SN metastases and the number of patients with SN micrometastases has been small. In the present study, the numbers of involved and uninvolved SN were the factors predicting NSN metastases. The numbers of involved and uninvolved SN were independent risk factors for NSN metastases also in the study by van Zee and co workers, who did not include the size of the metastasis in their analysis.18 NSN metastases seemed more common in patients with micrometastases detected already in the frozen section or when the size of the micrometatastasis was at least 1 mm, but the findings were not statistically significant. The latter finding is in agreement with an observation in a previous study stating the risk of NSN involvement in patients with micrometastases larger than 1 mm to be equal to that encountered in connection with SN macrometastases.15
The influence of the lymphatic mapping and the histological methods The likelihood of detecting SN micrometastases is correlated with the number of sections examined and the sectioning interval.15 If the SN metastasis is detected already in the intraoperative diagnosis, in the postoperative evaluation with H & E staining or
17 by IHC only is depending on the methods used in the assessment of SN metastases. The smallest micrometastases may remain undetected by the pathologist.19 Also the size of the metastasis may be underestimated, especially in the frozen section. In the present study, the SN micrometastasis detected in the frozen section proved to be a large one in almost every fourth patient. The lymphatic mapping methods, like the injection site, the dose, the volume and the particle size of the radioactive tracer, vary between the units leading to different numbers of axillary nodes removed as SN. Because a standard in the identification as well as in the histological examination of the SN is lacking, clinical decision making should not be based only on the observations made in other units. Furthermore, we recommend AC in all patients with SN metastases in the frozen section, because the size of the SN metastasis, the number of involved and uninvolved SN as well as the features of the primary tumour are not exactly known before the postoperative histopathological examination of the specimens.
The role of AC The advantage of AC in patients with tumour positive SN has been questioned.20 The risk of clinically manifest axillary recurrence seems to be negligible after omitting AC in patients with SN micrometastases, at least during a short followup.20 Furthermore, the NSABP B-04 study concluded no survival advantage of a prophylactic AC in clinically node negative patients.21 On the other hand, AC is proposed to provide not only excellent regional control but also a survival benefit independent of systemic adjuvant therapy.22–24 Abandoning axillary clearance in patients with SN metastases outside prospective trials is not advisable. However, omitting AC as second operation can be considered in patients with a single SN micrometatasis and several uninvolved SN and of course in patients with severe comorbidity.
Conclusions Every fourth patient will have residual disease in the axilla, 10% even large metastases, if AC is omitted in patients with SN micrometastases. The risk of NSN involvement seems negligible in patients with a single SN micrometastasis and several healthy SN harvested.
18
M.H.K. Leidenius et al.
Acknowledgements The study was supported by a grant from Helsinki University Hospital Research Fund.
12.
13.
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