High body mass index is associated with worse quality of life in breast cancer patients receiving radiotherapy.

The purpose of this study was to examine the impact of body mass index (BMI) on breast cancer patients' self-reported health-related quality of life among patients treated with radiation therapy (RT). Women with breast cancer undergoing RT were prospectively enrolled in an Institutional Review Board-approved clinical trial between 2009 and 2012. Quality of life (QOL) assessments were collected pre-RT, during RT, and within 3 months post-RT using Euroqol (EQ-5D), MD Anderson Symptom Inventory, and functional assessment of cancer therapy-general (FACT-G). 183 breast cancer patients were enrolled, of whom 140 completed assessments at one or more time-point. After adjusting for age, chemotherapy, prior RT, type of breast surgery, and comorbidities, higher BMI remained significantly associated with worse QOL pre-RT, during RT, and post-RT in breast cancer patients. Higher BMI was strongly associated with worse overall FACT-G score on treatment and greater decline in physical well-being on treatment, which persisted after treatment. While effects on QOL of patients in the underweight and normal weight group peaked during treatment, rapidly improving by follow-up, obese patients had worse functional well-being that was more persistent at follow-up. Higher BMI was associated with worse QOL for breast cancer patients before, during, and after RT, and also was associated with reduced return to baseline QOL 3 months post-RT.