The optimal surgical axillary staging technique in patients who convert from the clinically positive to clinically negative lymph node status under neoadjuvant therapy (cN+ → ycN0) remains to be clarified. Different strategies (axillary lymph node dissection, sentinel node biopsy, targeted axillary dissection) are currently used in different countries. A prospective analysis comparing these techniques regarding feasibility, safety, morbidity and surgical effort is urgently needed. Due to high complexity and discordant recommendations, a randomized trial comparing different techniques is hardly feasible. Therefore, the EUBREAST study group decided to initiate a prospective cohort study as an international project that aims at comparatively evaluating data on axillary staging after neoadjuvant therapy.