Axillary surgery in patients with sentinel node macrometastases: secondary results of the randomized INSEMA trial

The sub-study of the INSEMA trial (randomization-2) compares completion axillary lymph node dissection (cALND) with sentinel lymph node biopsy (SLNB) alone in cN0 patients with T1/T2 invasive breast cancer and one to three sentinel node macrometastases undergoing upfront breast-conserving surgery. The key secondary objective is to assess whether the SLNB-alone arm is non-inferior to cALND in terms of invasive disease-free survival (iDFS). Finally, 485 patients were recruited, and 386 patients (cALND: N = 169, SLNB alone: N = 217) were included in the per-protocol set. The median follow-up is 74.2 months. The 5-year iDFS analysis in the per-protocol set demonstrates a non-significant difference between study arms, with a hazard ratio (HR) of 1.69 (95% CI: 0.98-2.94) for SLNB alone compared to cALND. The 5-year iDFS rates are 86.6% (81.0%-90.7%) in the SLNB-alone arm and 93.8% (88.7%-96.6%) in the cALND arm (P = 0.058). The 5-year overall survival rates are 94.9% (90.6%-97.2%) in the SLNB-alone arm and 96.2% (91.7%-98.3%) in the cALND arm (P = 0.663). Locoregional recurrences (LRR) were infrequent, with 5-year incidence rates of 1.1% versus 0.0% (P = 0.405) in the SLNB-alone arm compared to cALND. In summary, no significant differences were observed between SLNB alone versus cALND for iDFS, overall survival, and LRR. Trial registration number: NCT02466737.