Abstract
Background. Axillary lymph node biopsy (ALND) has traditionally been considered the gold standard for axillary staging and treatment in clinically node-positive breast cancer patients. However, in patients with nodal disease, the therapeutic benefit of ALND is uncertain. This study, based on a large cohort, aims to evaluate breast cancer-specific survival depending on the extent of axillary surgery in non-metastatic breast cancer using real-world data from the Surveillance, Epidemiology, and End Results (SEER) database. Methods. This retrospective cohort study comprised 825,240 patients diagnosed with breast cancer between 2000 and 2020. Results. ALND was associated with a worse survival outcome in pN0 and pN1 populations (respectively, hazard ratio [HR] 1.16; 95% confidence interval [CI] 1.12-1.2; p < 0.001 and HR 1.38; 95%CI 1.3-1.46; p < 0.001). In pN2 and pN3 populations, there was ~4.3% relative reduction in the hazard of breast cancer-related death for each additional node removed; and higher positive-to-removed lymph node ratio was associated with worse prognosis (HR 3.450; 95%CI 2.99-3.98; p < 0.001). Conclusions. SLNB is associated with significantly better specific survival compared to ALND in negative/low axillary involvement, in higher axillary involvement categories extensive axillary surgery was associated with better prognosis.