Neo‐adjuvant chemotherapy and axillary de‐escalation management for patients with clinically node‐negative breast cancer

: This study aimed to explore the optimal time of sentinel lymph node biopsy (SLNB) and neo-adjuvant chemotherapy (NAC) and to assess the feasibility of selective elimination of axillary surgery after NAC in clinically node-negative (cN0) patients. From April 2010 to August 2018, 845 patients undergoing surgery after NAC were included in this retrospective study to analyze the correlation between different clinicopathological characteristics of cN0 patients and negative axillary lymph node after NAC (ypN0). Among the 148 cN0 patients, 83.1% (123/148) were ypN0. The rates of ypN0 in patients with hormone receptor positive (HR+)/HER2-, HR+/HER2+, HR-/HER2+, and triple-negative (TN) breast cancer were 75.4% (46/61), 82.6% (19/23), 85.2% (23/27), and 94.6% (35/37), respectively (P < 0.001). The rates of ypN0 in TN and HER2+ patients were 94.6% and 95.5%, which were significantly higher than that in HR+/HER2- patients (P < 0.05). Molecular subtypes, clinical stage, radiologic complete response, and pathologic complete response (bpCR) of the breast tumor correlated with ypN0 after full-course NAC (P < 0.05). Molecular subtypes (OR = 2.374, P = 0.033), clinical stage (OR = 0.320, P = 0.029), and bpCR (OR = 0.454, P = 0.012) were independent predictors for ypN0. The optimal time of SLNB and NAC in cN0 patients might be different among different molecular subtypes: it would be preferable to perform SLNB prior to NAC for HR+/HER2- patients, and SLNB after NAC for TN and HER2+ patients to reduce the risk of axillary lymph node dissection. In view of the high ypN0 rate in cN0 patients, axillary surgical staging might be selectively eliminated, especially for HER2+ and TN patients.