Surgical Management of Axilla of Triple-Negative Breast Cancer in the Z1071 Era: A Propensity Score-Matched Analysis of the National Cancer Database.

Abstract

The role of sentinel lymph node biopsy (SLNB) in triple-negative breast cancer (TNBC) patients who present with clinical N1 (cN1) disease and undergo complete clinical response (cCR) to neoadjuvant systemic therapy (NAST) remains unclear. We aimed to study the outcomes of SLNB versus axillary lymph node dissection (ALND) in this setting. Patients with cN1 TNBC who showed cCR to NAST were selected from the National Cancer Database (NCDB), and propensity score matched 1:1 between SLNB and ALND in all-comers, ypN0, and ypN1 subgroups. Overall survival (OS) was compared using the Kaplan-Meier method. Cox regression was used to identify predictors of OS. Of the 2953 patients selected. 1062 (36.0%) underwent SLNB and 1891 (64.0%) underwent ALND. There was a chronological increase in national SLNB utilization (from 20% in 2012 to 46% in 2017). One thousand three patients were propensity matched between SLNB and ALND, and no OS difference was noted (81.73 ± 1.04 vs. 80.07 ± 0.70 months; p = 0.127). In the ypN0 subgroup, 884 pairs were matched and no significant OS difference was found (85.29 ± 0.84 vs. 82.60 ± 0.68 months; p = 0.638). In ypN+ patients, 129 pairs were matched and demonstrated a trend toward decreased OS with SLNB (64.37 ± 3.12 vs. 72.45 ± 72.45; p = 0.085). Cox regression identified age, inner tumors, advanced T stage, partial/no in-breast response, and nodal status as unfavorable predictors of OS. Definitive axillary surgical procedure was not a predictor in the final model. SLNB and ALND appear to yield comparable OS in cN1 TNBC patients who demonstrate cCR to NAST. Caution should be exercised in ypN1 patients as worse OS could be associated with SLNB.