Omission of Axillary Lymph Node Dissection in Case of Tumor Spread to Lymph Nodes in the Armpit in Breast Cancer

SENOMAC-ULTRA enrols patients who are planned for upfront surgery for a breast cancer that has spread to lymph nodes in the armpit, and that have been detected already prior to surgery by imaging, e.g. ultrasonography. In this situation, a full axillary lymph node dissection, removing more than 10 lymph nodes from the arm pit, is unnecessarily extensive in about half of the patients. More extensive surgery leads to a risk for arm lymphedema and functional problems with the arm and shoulder region, which should be avoided if not beneficial for diagnosis or prognosis. This trial seeks to ascertain that less extensive surgery, performed by only removing the first lymph node/s in the armpit (the sentinel lymph node/s) and the known metastatic lymph nodes (targeted axillary dissection, TAD), offers non-inferior survival outcomes to a full axillary lymph node dissection.