Axillary Surgery in Breast Cancer — Primary Results of the INSEMA Trial

Whether surgical axillary staging as part of breast-conserving therapy can be omitted without compromising survival has remained unclear.

In this prospective, randomized, noninferiority trial, we investigated the omission of axillary surgery as compared with sentinel-lymph-node biopsy in patients with clinically node-negative invasive breast cancer staged as T1 or T2 (tumor size, ≤5 cm) who were scheduled to undergo breast-conserving surgery. We report here the per-protocol analysis of invasive disease-free survival (the primary efficacy outcome). To show the noninferiority of the omission of axillary surgery, the 5-year invasive disease-free survival rate had to be at least 85%, and the upper limit of the confidence interval for the hazard ratio for invasive disease or death had to be below 1.271.