Regional Recurrence Rates With or Without Complete Axillary Dissection for Breast Cancer Patients with Node-Positive Disease on Sentinel Lymph Node Biopsy after Neoadjuvant Chemotherapy

PURPOSE: Current standard of care for patients with breast cancer with a positive node on sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy is axillary dissection with irradiation of the regional nodes, but it is unknown whether axillary lymph node dissection (ALND) can be safely omitted if complete axillary radiation is delivered instead. METHODS AND MATERIALS: We identified 161 patients found to have a positive sentinel lymph node on SLNB after neoadjuvant chemotherapy for breast cancer between December 2006 and October 2017, who were treated with or without completion ALND. Local, regional, and distant recurrence and overall survival were analyzed using the Kaplan-Meier method. Patient, disease, and treatment factors potentially predictive of each outcome were entered into Cox regression analysis. RESULTS: Median follow-up was 28.8 months (range, 2.5-137.0). The 3-year regional control rate did not differ according to extent of axillary surgery (92.6% for SLNB alone vs 96.4% for SLNB with ALND, P = .616). Regional recurrence occurred as part of first recurrence in 9 patients (5.6%). Five patients failed in axillary levels 1 or 2, 6 failed in axillary level 3 or supraclavicular nodes, and 2 failed in internal mammary nodes, with some patients failing in multiple regional nodal areas. Extent of axillary dissection (SLNB only vs SLNB plus ALND) did not predict for disease control or survival. Patients who underwent ALND were significantly more likely to have lymphedema (25.0% vs 9.4%, P = .021). CONCLUSIONS: Careful selection of patients with a positive sentinel node on SLNB after neoadjuvant chemotherapy for omission of completion ALND in favor of irradiation of the undissected axilla does not compromise local, regional, or distant control or overall survival and results in lower rates of lymphedema.