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

Locoregional Control With Radiotherapy of cT1-2N0 Invasive Breast Cancer Patients With MACrometastases in the Sentinel Node Treated With MAstectomy: a Multi-center Observational Study

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.

This is a multi-center, prospective study with an estimated sample size of 60 early-stage IBC patients.

Clinically node-negative T1-2 IBC patients undergoing mastectomy with up to 2 macrometases after SLNB will be informed about this study.

Patients will be checked with annual mammography and clinical examination. The axilla will be checked with ultrasound at 3 and 5 years of the surgery.

After surgery, patients will receive axillary radiotherapy, but no ALND, and adjuvant systemic treatment based on international guidelines.

Inclusion Criteria:

• Patients with T1-2 primary invasive breast cancer
• No suspicion of lymph node involvement prior to sentinel lymph node biopsy
• Patients undergoing upfront mastectomy
• Macrometastasis in not more than 2 lymph nodes at sentinel lymph node biopsy
• Patients treated with adjuvant axillary radiotherapy

Exclusion Criteria:

• Prior history of invasive breast cancer
• Medical contraindication for radiotherapy
• Medical contraindication for adjuvant systemic treatment
• Planned neoadjuvant systemic treatment
• Distant metastasis at initial diagnosis
• Inability to absorb or understand the meaning of the study information