Outcomes and Trends in Axillary Management of Stage cN3b Breast Cancer Patients.

Background: There is limited data regarding sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) for cN3b patients, who present with both axillary and ipsilateral internal mammary node involvement. We examined trends in the use of SLNB in cN3b patients and survival by axillary procedure for those with nodal pathologic complete response (nPCR).

Methods: Adult women with nonmetastatic cN3b invasive breast carcinoma between 2012 and 2021 were selected from the National Cancer Database. These patients were compared based on type of axillary surgery, specifically SLNB, SLNB with axillary lymph node dissection (ALND), and ALND alone. Kaplan-Meier analysis was used to compare overall survival.

Results: A total of 4,236 patients were included. In 2012, 8.5% of these patients underwent SLNB alone and 18.3% underwent SLNB+ALND. In 2021, this increased to 35.1% for SLNB alone and 23.0% for SLNB with subsequent ALND (p < 0.0001). For patients who received NAC, the rate of nPCR was overall found to be 24.9%. Overall survival of patients receiving SLNB or SLNB+ALND with nPCR was not statistically significantly different from the ALND only group with nPCR (p = 0.22 and 0.57, respectively).

Conclusions: There has been increasing use of the SLNB procedure for patients with cN3b breast cancer over the past decade. In patients with nPCR, SLNB was not associated with reduced survival. For well-selected cN3b patients with an excellent clinical response to NAC, including nPCR, axillary de-escalation strategies, such as SLNB with omission of completion axillary dissection, may be considered.