RESUMEN
BACKGROUND: Low false negative rates can be achieved with sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) in breast cancer (BC) patients with clinical N1 (cN1) disease. We examined changes in axillary management and oncologic outcomes in BC patients with cN1 disease receiving NAC. METHODS: BC patients with biopsy proven cN1 disease treated with NAC were selected from our institutional cancer registry (2014-2017). Patients were grouped by axillary management, axillary lymph node dissection (ALND), SLNB followed by ALND, or SLNB alone. Univariable and multivariable survival analysis for recurrence-free survival (RFS) and overall survival (OS) were performed. RESULTS: 81 patients met inclusion criteria: 31 (38%) underwent ALND, 25 (31%) SLNB + ALND, and 25 (31%) SLNB alone. A SLN was identified in 45/50 (90%) patients who had SLNB. ALND was performed in 25/50 (50%) patients who had SLNB: 18 for a + SLNB, 5 failed SLNB, and 2 insufficient SLNs. 25 patients had SLNB alone, 17 were SLN- and 8 SLN+. In the SLNB alone group, 23/25 (92%) patients received adjuvant radiation (RT). 20 (25%) patients developed BC recurrence: 14 distant (70%), 3 local (15%), 2 regional + distant (10%), and 1 contralateral (5%). In the SLNB alone group, there was 1 axillary recurrence in a patient with a negative SLNB who did not receive RT. Univariable survival analysis showed significant differences in RFS and OS between axillary management groups, ALND/SLNB + ALND vs. SLNB alone (RFS: p = 0.006, OS: p = 0.021). On multivariable survival analysis, worse RFS and OS were observed in patients with TNBC (RFS: HR 3.77, 95% CI 1.70-11.90, p = 0.023; OS: HR 8.10, 95% CI 1.84-35.60, p = 0.006). CONCLUSIONS: SLNB alone and RT after NAC in BC patients with cN1 disease who have negative SLNs at surgery provides long-term regional disease control. This analysis provides support for the practice of axillary downstaging with NAC and SLNB alone.