Sentinel Node Biopsy Versus Low Axillary Sampling in Predicting Nodal Status of Postchemotherapy Axilla in Women With Breast Cancer

Abstract

PURPOSE We tested low axillary sampling (LAS) and sentinel node biopsy (SNB) performed in the same patient to predict axillary nodal status post–neoadjuvant chemotherapy (NACT) in women undergoing elective breast surgery, clinically N0 after NACT. PATIENTS AND METHODS A total of 751 women clinically node negative post-NACT underwent LAS (excision of lymph node [LN] and fat below first intercostobrachial nerve). Of these women, 730 also underwent SNB by dual technique (methylene blue plus radioisotope). SNB (defined as targeted plus palpable LNs) and LAS specimens were distinctly examined for metastasis. All patients underwent completion axillary lymph node dissection. Post-NACT, 290 (38.6%) of 751 women had residual positive lymph nodes on pathology. RESULTS The median clinical tumor size was 5 cm (range, 1-15 cm), and 533 (71%) of patients were N1 or N2 at presentation. Targeted sentinel node (SN) identification was 85.7% (626 of 730; median, two LNs); SN with palpable nodes was found in 95.2% (695 of 730; median, five LNs); LAS node was identified in 98.5% (740 of 751; median, seven LNs). In all but one case, the SN was found within the LAS specimen. The false negative rate (FNR) of SNB (blue, hot, and adjacent palpable nodes) was 19.7% (47 of 238; one-sided 95% CI upper limit, 24.0), compared with an FNR of 9.9% for LAS (29 of 292; one-sided 95% CI upper limit, 12.8; P < .001). If SNB was confined to blue/hot node, excluding adjacent palpable nodes, the FNR was 31.6% (74 of 234; one-sided 95% CI upper limit, 36.6). The FNR could be brought down to < 8.8% if three or more LNs were identified by LAS. CONCLUSION LAS is superior to SNB in identification rate, FNR, and negative predictive value in predicting node-negative axilla post-NACT. LAS can be safely used to predict negative axilla with < 10% chance of leaving residual disease.