The Past, Present, and Future of Sentinel Lymph Node Biopsy in Breast Cancer.

Sentinel lymph node biopsy (SLNB), the current gold standard for axillary staging for many breast cancer patients, has replaced axillary lymph node dissection (ALND) for clinically node-negative patients due to lower surgical morbidity while maintaining oncologic safety. Advances in breast cancer surgery, axillary staging, lymphatic mapping, targeted axillary dissection (TAD), neoadjuvant chemotherapy (NAC), and sentinel lymph node (SLN) identification techniques have reshaped axillary management and enabled progressive de-escalation of surgical treatment. This review examines the historical development, current clinical applications, and emerging innovations in SLNB. Early randomized trials including the NSABP B-32 and ALMANAC trials established SLNB as a safe alternative to ALND for clinically node-negative patients with comparable overall survival (OS), disease-free survival (DFS), and regional control while significantly reducing complications such as lymphedema. Subsequent trials including ACOSOG Z0011, IBCSG 23-01, and AMAROS further supported omission of completion ALND (cALND) for selected patients with limited SLN metastases. In the neoadjuvant setting, studies such as ACOSOG Z1071, SENTINA, and SN-FNAC evaluated SLNB accuracy after NAC and informed the development of optimized techniques, including dual-tracer mapping and TAD, to reduce false-negative rates. Technological advances including indocyanine green fluorescence imaging, technetium-99m radiotracers, and superparamagnetic iron oxide tracers have further improved SLN identification. Ongoing trials investigating SLNB omission and imaging-guided axillary staging continue to refine patient selection and advance the shift toward personalized, morbidity-conscious axillary management.