Post-neoadjuvant chemotherapy sentinel node biopsy and axillary sampling for node negative (N0) axilla.

Abstract

1108 Background: Post neoadjuvant chemotherapy (NACT) sentinel node biopsy (SNB) is not a standard of care due to the wide variability in false negative rate (FNR), varying from 5.7% to 33%. In operable breast cancer (OBC), FNR of less than 10% is acceptable. We attempted to find out the reliability of low axillary sampling(LAS), with dissection limited below the first intercostobrachial nerve, to correctly identify the node negative axilla in the post NACT clinically node negative (N0) patients. Methods: Women with large operable (LOBC) and locally advanced breast cancer (LABC), post-NACT clinically N0, underwent concomitant blue dye-colloid guided SNB and LAS. The identification rate, FNR, and negative predictive value (NPV) of both procedures were compared. Results: Post-NACT 209 eligible women underwent combined LAS and SNB procedure. At presentation, the tumors were large (median 5.0 cm) with 70% clinically palpable nodes. All patients received 4 cycles of neo-adjuvant anthracycline-based chemotherapy and were clinically node negative after chemotherapy. SNB was defined as blue and/or hot node plus palpable node(s). A blue or hot node (median 2 nodes) was identified in 93.8%, and median of 5 sentinel nodes were removed. The false negative rate of SNB was 15.3% (95% CI 8.7%-25.3%). The LAS technique comparatively had nodal yield in 98.5% with median 8 nodes removed; and FNR 8.5% (95% CI, 4.2%-16.6%, p=0.19). Comparative NPV for LAS and SNB were 94.6% and 91.8% respectively. Conclusions: Axillary sampling results for FNR and NPV are similar if not superior to SNB and could be a reliable method of axillary nodal evaluation in advanced breast cancers following neo-adjuvant chemotherapy.