Hypofractionated Regional Nodal Irradiation in Breast Cancer

This is a prospective clinical trial designed to evaluate the efficacy and safety of hypofractionated regional nodal irradiation in breast cancer patients. Participants are stratified into 2 Groups based on the extent of axillary surgery after enrollment. Group 1: sentinel lymph node procedure with or without select removal of clipped (clinically involved) lymph nodes. Group 2: axillary lymph node dissection (with or without sentinel lymph node procedure) or patients who have more than 5 sentinel lymph nodes removed will be stratified into group 2. Participants will complete activities and assessments at baseline, and after completion of treatment at 1-2 weeks, 3 months, 6 months, 1 year, 2 year, and 3 years following completion of treatment. At baseline consultations, history and physical, lymphedema assessment, toxicity assessment, photographs (optional), patient-reported outcome questionnaire and radiation simulation will be completed. Hypofractionated radiation therapy will be completed weekly through the end of treatment with toxicity assessments. At the 1-2 week follow up, toxicity assessment, photographs (optional) and the patient-reported outcome questionnaire will be completed. At the 3 month, 6 month, 1 year, 2 year and 3 year follow-ups a lymphedema assessment, toxicity assessment, photographs (optional), patient-reported outcome questionnaire and follow up examination will be completed. All patients will receive a dose of 42.56 Gy in 16 daily fractions to the whole breast or chest wall and regional lymph nodes. A boost dose of 10 or 12.5 Gy in 4 or 5 daily fractions of 2.5 Gy, respectively, will be administered to either the lumpectomy cavity or mastectomy scar, as appropriate. Critical organs will be contoured into the treatment planning such as the heart, left anterior descending artery, ipsilateral lung. Patients may receive neoadjuvant or adjuvant systemic treatment on this trial. In general, the patient should receive systemic treatment according to the current standard of care at the time of enrollment, taking into account the discretion of the treating medical oncologist. Expected radiation-related acute adverse events (i.e., those experienced within the first 6 months following treatment) are similar to those with conventionally fractionated radiotherapy and include fatigue and tenderness, pruritus, hyperpigmentation, hypopigmentation, dry desquamation, and moist desquamation of the skin. Potential late effects of radiation include arm lymphedema, shoulder stiffness, fibrosis of normal tissue, telangiectasia, hyperpigmentation, or hypopigmentation of the skin, brachial plexopathy, myositis, rib fracture, pneumonitis, second malignancy, or cardiomyopathy. The participants will be monitored for adverse events during radiotherapy and following radiotherapy.