Body mass index, physical activity, and health-related quality of life in cancer survivors

Purpose: To determine the independent and interactive associations among body mass index (BMI), physical activity (PA), and health-related quality of life (HRQoL) in breast, prostate, colorectal, bladder, uterine, and skin melanoma cancer survivors. Methods: A total of 3241 cancer survivors completed a national cross-sectional survey that included PA questions and the RAND-36 Health Status Inventory. Results: Compared with healthy-weight survivors, obese breast, prostate, bladder, and skin melanoma cancer survivors were significantly less likely to meet the PA guideline. Furthermore, healthy-weight and/or overweight breast, prostate, colorectal, uterine cancer, and skin melanoma survivors reported significantly better physical functioning compared with their obese counterparts, whereas overweight colorectal cancer survivors reported significantly better mental health compared with obese survivors. Finally, hierarchical linear regressions showed that none of the BMI × PA interactions was significant for the physical or mental component composite scores across the cancer types. Conclusions: The percentage of cancer survivors meeting the American Cancer Society's PA guideline seems to vary by weight status in breast, prostate, bladder, and skin melanoma cancer survivors. In addition, BMI and PA have independent associations with HRQoL; however, the interactive association of BMI and PA on HRQoL was negligible. Clarifying the relationship between BMI and PA across different cancer types will help identify potential target groups for future PA interventions that will help ameliorate the negative side effects of cancer and improve HRQoL.