Sentinel node biopsy alone for breast cancer patients with residual nodal disease after neoadjuvant chemotherapy

For residual N1 nodal disease following neoadjuvant chemotherapy (NAC) for patients with breast cancer, the optimal local therapy for axilla is an evolving area. We analyzed the long-term results of these patients according to axillary surgical methods using propensity score matching (PSM) to clarify whether omission of axillary lymph node dissection (ALND) is oncologically safe. This was a single institution retrospective study of patients with ypN1 from Asan Medical Center (AMC). We included 324 patients who had undergone axillary surgery with either sentinel lymph node biopsy (SLNB) only or ALND. The patients received NAC at AMC between 2008 and 2013. General indications for ALND included prominent nodes detected clinically before NAC, evident macrometastasis on multiple nodes during SLNB. Patients who had either micrometastasis or macrometastasis in 1 or 2 node(s) were included. SLNB was performed for patients with good responders to NAC with limited nodal burden. Patients were matched for baseline characteristics. After matching, we included 98 patients in each SLNB only group and ALND group respectively. We compared axillary recurrence-free survival (ARFS), distant metastasis-free survival (DMFS), overall survival (OS), and breast cancer-free survival (BCSS) according to the surgical method. The median follow-up period was 71 months. Univariate and multivariate analyses revealed no statistically significant differences between the two groups for ARFS, DMFS, OS, and BCSS. After the propensity score matching, no significant statistical differences were observed in 5-year ARFS, DMFS, OS, and BCSS between the SLNB only group and ALND group. SLNB might be a possible option for ALND in patients with breast cancer who have limited axillary node metastasis after NAC without compromising survival outcomes.