Patient-reported fatigue in breast cancer patients receiving radiation therapy.

•Fatigue is a common symptom in breast cancer patients treated with radiation therapy (RT), and can have a significant impact on quality of life.•We aimed to identify patient, disease, and treatment variables associated with fatigue scores pre- and post-breast RT in 1223 patients.•Pre-RT fatigue was associated with higher disease stage and receipt of locoregional RT.•Reductions in fatigue were found in patients who received locoregional RT and adjuvant chemotherapy despite higher baselines.•This study suggests that disease and treatment factors may influence severity and development of fatigue before, during and after radiation therapy.