Locoregional Control With Radiotherapy of Breast Cancer Patients With MACrometastases Treated With MAstectomy (MACMA)

Sentinel lymph node biopsy (SLNB) is the standard procedure to stage the axilla in clinically node-negative invasive breast cancer (IBC) patients undergoing upfront surgery. The ACOSOG-Z0011 and the AMAROS trial demonstrated that SLNB with or without radiotherapy provided equivalent local control and survival to axillary lymph node dissection (ALND) in early-stage breast cancer patients with 1 or 2 positive SLNs. However, the ACOSOG-Z0011 trial did not included patients treated with mastectomy, and the AMAROS trial only included 17% of mastectomy patients. The investigators conduct an observational cohort study of early stage breast cancer patients receiving upfront mastectomy with 1 or 2 macrometastases after SLNB. The study aim to demonstrate a 5-year disease-free survival of not less than 80% when ALND is omitted and replaced by axillary radiotherapy, and determine the axillary recurrence rate.