Efficacy and Safety of Ultra_HYPofractionated RadiotHerapy in Women With BrEast CaNcer Receiving Regional Nodal Radiation vs Nodal Moderate Hypofractionated Radiotherapy

The reduction in the number of fractions in radiotherapy is especially attractive in several senses, and even more so considering breast cancer, which has a high incidence and generally favorable prognosis. Thus, as a reference Institution, the investigators intend to start the treatment of selected patients with a radiotherapy scheme of 26 Gy / 5 fractions in one week, in a controlled manner, through this project.The investigators consider the moment extremely propitious to start the study, as in addition to having the first publication of a large randomized study, proving the effectiveness and safety of the strategy, the investigators will be able to benefit more patients and the health system itself by minimizing the daily visits of these patients at the hospital.

Inclusion Criteria:Information to the patient and signed informed consent;Women aged ≥18 years;Breast conserving surgery;Invasive adenocarcinoma (except classic invasive lobular carcinoma);TNM (Tumor, Nodes, Metastasis) pathologic stage pT1-3 and pN1-3a M0, with indication of lymphatic drainage according to institutional protocol;Eastern Cooperative Oncology Group (ECOG) 0 -1;Minimum microscopic margin of non-cancerous tissue of 2 mm (excluding deep margin if in the deep fascia);No previous breast or mediastinal radiotherapy;No hematogenous metastases;Ability to carry out long-term follow-up;Exclusion Criteria:Previous local irradiation;Concomitant chemotherapy. Concomitance with trastuzumab or hormone blockade will be allowed;Histology of metaplastic carcinoma;History of another neoplasm: non-melanoma skin cancer, carcinoma in situ of the uterine cervix. Another neoplasm treated with curative intent and without evidence of disease in the last 5 years will be allowed.Diagnosis of autoimmune and connective tissue diseases;Diagnosis of genetic alterations in cell repair genes (Ex: Fanconi anemia, ataxia teleangiectasia);Indication of internal breast irradiation.