Factors Associated with Omission of Axillary Lymph Node Dissection for Patients with Clinical Node-Positive Breast Cancer Who have Residual Nodal Disease on Pathology After Neoadjuvant Chemotherapy

BACKGROUND: For breast cancer patients with clinically node-positive (cN+) and residual disease after neoadjuvant chemotherapy (NAC), axillary lymph node dissection (ALND) remains the standard of care, though alternative strategies may be selected by multidisciplinary teams in certain cases. This study evaluated factors associated with omission of ALND for cN+ patients who were pathologically node-positive after NAC (ypN+). METHODS: In this retrospective observational study, the National Cancer Database was queried for patients with clinical T1-T4, N1-N3 breast cancer from 2016 to 2021 who received NAC and were subsequently ypN+. Axillary procedures were categorized as sentinel lymph node biopsy (SLNB) alone, SLNB followed by ALND (SLNB + ALND), or ALND alone. Logistic regression identified factors associated with omission of ALND after SLNB, adjusting for sociodemographic, geographic, and clinical variables. RESULTS: Among 38,559 patients, axillary interventions were SLNB alone (n = 7,131, 18.49%), SLNB+ALND (n = 14,247, 36.95%), and ALND alone (n = 17,179, 44.55%). Over the study period, SLNB alone and SLNB + ALND increased while ALND alone decreased. Compared with academic programs, patients treated at comprehensive community, integrated network, and community programs had greater odds of SLNB alone compared with SLNB+ALND (odds ratio [OR] 1.32, 95% confidence interval [CI] 1.22-1.43; OR 1.17, 95% CI 1.07-1.27; OR 1.54, 95% CI 1.33-1.78, respectively). CONCLUSIONS: There has been de-escalation of ALND after initial SLNB for cN+ breast cancer patients found to be ypN+. This suggests that providers may be extrapolating evidence supporting SLNB alone to populations in which it has not yet been thoroughly studied or are omitting ALND in anticipation of ongoing clinical trial results.