Omitting Surgical Axillary Staging: SOUND, INSEMA, BOOG 2013-08 and the NCCN Shift in Axillary Management

Axillary management in early breast cancer has undergone sustained de-escalation, from routine axillary lymph node dissection (ALND) to sentinel lymph node biopsy (SLNB) and, most recently, to the selective omission of any surgical axillary staging. Three randomized trials now address omission directly. SOUND randomised 1,405 patients with tumours of 2 cm or less and a negative axillary ultrasound; at a median follow-up of 5.7 years, five-year distant disease-free survival was 98.0% with omission versus 97.7% with SLNB (hazard ratio 0.84, 90% CI 0.45-1.54; non-inferiority P = 0.02), with a five-year cumulative incidence of axillary recurrence of 0.4% in each arm. INSEMA randomized 4,858 evaluable patients; at a median follow-up of 73.6 months, five-year invasive disease-free survival was 91.9% versus 91.7% (hazard ratio 0.91, 95% CI 0.73-1.14), with axillary recurrence of 1.0% after omission versus 0.3% after SLNB. BOOG 2013-08, reported in abstract form, randomized 1,572 evaluable patients; the five-year estimated probability of regional recurrence was 1.2% after omission versus 0.5% after SLNB (absolute difference 0.7%, 95% CI -0.3 to 1.7), within the prespecified 5% non-inferiority margin, with five-year distant disease-free survival of 96.1% versus 98.3%. Based on SOUND and INSEMA, the 2026 NCCN Breast Cancer guideline (Version 2.2026) added a footnote stating that patients over 50 years and postmenopausal with cT1N0 disease (node negative by axillary ultrasound), HR-positive and HER2-negative grade 1-2 tumors, who are agreeable to receiving whole breast radiotherapy and endocrine therapy, may be considered for omission of SLNB, with caution advised in lobular histology. The panel simultaneously retired an earlier single-trial footnote and a separate Choosing Wisely provision for patients aged 70 years or older, and now advises obtaining an axillary ultrasound when omission of surgical nodal staging is being considered. This review traces the evolution of axillary de-escalation, presents the quantitative findings and eligibility criteria of the omission trials, documents the precise scope of the NCCN 2026 recommendation, and analyses the principal unresolved tension: the loss of pathological nodal information increasingly required to select adjuvant CDK4/6 inhibitor and genomic-assay-directed therapy. An explicitly labeled framework for safe institutional implementation is proposed, along with the residual uncertainties regarding lobular histology, ultrasound quality, and the mastectomy setting.