Axillary response rates to neoadjuvant chemotherapy in breast cancer patients with advanced nodal disease

Purpose Utilization of sentinel lymph node biopsy (SLNB) in breast cancer patients with positive nodes after neoadjuvant chemotherapy (NAC) has increased. We examine axillary response rates after NAC in patients with clinical N2-3 disease to determine whether SLNB should be considered. Methods Breast cancer patients with clinical N2-3 (AJCC 7th Edition) disease who received NAC followed by surgery were selected from our institutional tumor registry (2009-2018). Axillary response rates were assessed. Results Ninety-nine patients with 100 breast cancers were identified: 59 N2 (59.0%) and 41 (41.0%) N3 disease; 82 (82.0%) treated with axillary lymph node dissection (ALND) and 18 (18.0%) SLNB. The majority (99.0%) received multiagent NAC. In patients undergoing ALND, cCR was observed in 20/82 patients (24.4%), pathologic complete response (pCR) in 15 patients (18.3%), and axillary pCR in 17 patients (20.7%). In patients with a cCR, pCR was identified in 60.0% and was most common in HER2+ patients (34.6%). Conclusion In this analysis of patients with clinical N2-3 disease receiving NAC, 79.3% of patients had residual nodal disease at surgery. However, 60.0% of patients with a cCR also had a pCR. This provides the foundation to consider evaluating SLNB and less extensive axillary surgery in this select group.