Pooled analysis from five randomized trial of lymph node surgery and CDK4/6 inhibitors in early-stage breast cancer

Omitting sentinel lymph node biopsy (SLNB) and completion axillary lymph node dissection (cALND) in early-stage breast cancer reduces morbidity without compromising overall survival or recurrence rates. However, reduced axillary surgery restricts staging information, impacting eligibility for CDK4/6 inhibitors. Pooled analysis of five randomized trials (SOUND, INSEMA, SENOMAC, monarchE, and NATALEE) evaluated the impact of omitting SLNB or cALND on CDK4/6 inhibitor eligibility and the associated benefits and harms. A total of 19,541 patients were randomly assigned. The median follow-up was 57.2 months (IQR 44.1-81.6). For SLNB and ribociclib, the number needed to diagnose and treat for one prevented event was 123 for invasive disease-free survival, 129 for distant disease-free survival, and 345 for overall survival. For cALND and abemaciclib, the corresponding numbers were 106, 119, and 807. The authors conclude that performing SLNB or cALND solely to determine eligibility for CDK4/6 inhibition requires very high numbers needed to diagnose and treat, adds substantial morbidity, and is costly, with only marginal overall survival benefit.