Feasibility of de-escalating axillary surgery in patients with clinical N2–3, pathological N0 breast cancer after neoadjuvant chemotherapy

Axillary lymph node dissection (ALND) omission improves quality of life but is only considered under certain conditions. We investigated expanding these conditions in patients receiving neoadjuvant chemotherapy (NAC) for clinical N2-3, pathological N0 breast cancer. We retrospectively reviewed data of 1346 patients with clinical N2-3, M0, who underwent surgical resection (sentinel lymph node biopsy [SLNB] only, or level I-II ALND with/without SLNB) following NAC from January 2008 to December 2021. Univariate and multivariate analyses of overall (OS), disease-free (DFS), regional recurrence-free (RFS), and axillary recurrence-free survival (ARFS) were performed before and after propensity score matching (PSM) to control for confounding factors. Of the total patients, 521 (37.5%) achieved an axillary pathological complete response (ypN0). Of these, 293 (56.2%) underwent SLNB only. The median OS was 52.7 months. After PSM, SLNB-only and ALND groups showed no significant differences in ARFS (long-rank p = 0.765), RFS (long-rank p = 0.764), DFS (long-rank p = 0.186), and OS (long-rank p = 0.760). The 5-year ARFS (97.3 vs. 96.7%) and OS (97.7 vs. 97.3%) of both groups did not differ significantly. ALND omission after NAC in clinical N2-3, pathological N0 patients was not inferior to ALND,. Clinical N2-3 patients achieving ypN0 following NAC may be safely treated with SLNB alone.