Abstract P1-01-03: Accuracy of Sentinel Lymph Node Biopsy in Large and Multifocal/Multicentric Breast Carcinoma — Systematic Review

Abstract

Abstract Introduction: Sentinel lymph node biopsy (SLNB) is well established for management of small unifocal breast cancers. As confidence in SLNB increases, use of SLN-based management has increased and it is now often used for axillary staging in cases of multifocal (MF) and multicentric (MC) breast cancer and larger tumors although its role in the management of these tumors is controversial. The aim of this study is to systematically review the evidence for SLNB in axillary staging for newly diagnosed invasive breast cancer that is MF/MC or greater than 30mm in diameter. Studies reporting accuracy of SLNB in these situations are reviewed and implications for patient management are discussed. Methods: Medline was searched, identifying 3,461 studies of SLNB in breast cancer. Of these, 57 abstracts met the eligibility criteria which were: (a) original studies that reported (b) outcomes of SLNB in invasive breast cancer and (c) outcomes separately for a population of women with tumors that were either MF/MC or diameter 30mm or greater. Following review of full text articles, 36 studies were excluded as they did not meet criteria; two more studies were added after review of reference lists. Results: 23 studies met inclusion criteria and reported 20,687 cases of SLNB. This included data on accuracy for 1,541 MF, 369 MC, and 1,646 larger tumors. All included studies were case series; no randomized controlled trials were identified. Injection for lymphatic mapping was variably performed in site and technique and was variably reported. For MF cancers (n=976; 8 studies), success rate for identification of a SLN was 86-100%, SLN positivity rate 42-59%, false negative rate (FNR) 6-33%(with 4 of the 7 case series reporting false negative rates over 21%). The overall accuracy for MF tumors was 75-97%. For MC cancers (n=262; 4 studies): success rate for identification of a SLN 92-96%, SLN positivity rate 50-61%, FNR 0-8% and accuracy 96-100%. For ‘multiple breast cancer’ (n=688; 8 studies combining MF/MC cases): success rate for identification of a SLN 93-100%, SLN positivity rate 11-63%, FNR 6-13%, and accuracy 93-98%. For larger tumors (n=1646; 9 studies): success rate for identification of a SLN 86-100%, SLN positivity rate 42-59%, FNR 3-16.2% and accuracy 88-97.7%. For MF/MC and larger cancers overall non-SLN positivity rates were up to 82%; axillary recurrence rates were low but not often reported. Conclusion: Although the evidence suggests that success rate and FNR of SLNB in MF/MC and larger tumors are similar to small unifocal cancers, node positivity rates are higher in these breast cancers and this translates to higher rates of understaging in real terms. High rates of non-SLN positivity for these tumors compared to rates for lower risk tumors mean that omitting ALND in the case of a positive SLNB risks leaving disease in the axilla more often than previously accepted. Thus the evidence supports the use of ALND in the majority of cases when the SLNB is positive. Women must be made aware that the high likelihood of positive axillary lymph nodes in MF/MC and larger breast tumors. Relying on SLNB-based management means accepting a higher risk of understaging and/or under treatment than when using SLNB based management for lower risk tumors. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-01-03.