Prognostic Significance of Residual Axillary Nodal Micrometastases and Isolated Tumor Cells After Neoadjuvant Chemotherapy for Breast Cancer

Background The prognostic significance of low-volume residual nodal disease following neoadjuvant chemotherapy (NAC) is unknown. Methods Women with cT1–4N0–1 breast cancer treated with NAC were identified from Dana-Farber/Brigham and Women’s Cancer Center (DFBWCC) and the National Cancer Database (NCDB). Disease-free survival (DFS) and overall survival (OS) estimates according to pathologic nodal status were calculated using the Kaplan–Meier method, with Cox proportional hazards regression used to assess the effect of clinical variables on survival outcomes. Results Among 967 DFBWCC patients, 27 (2.8%) had residual isolated tumor cells (ITCs) and 61 (6.3%) had micrometastases. Five-year DFS was significantly worse in those with residual ITCs (73.5%) and micrometastases (74.7%) relative to those who were ypN0 following NAC (88.4%, p