Guideline-based physical activity and health-related quality of life among prostate cancer survivors: a target trial emulation in the Health Professionals Follow-up Study.

Prostate cancer and its treatment can impact health-related quality of life. Evidence for physical activity strategies sustained over long periods to improve quality of life is limited. Given the limited feasibility of a randomized trial to answer this question, we emulated a target trial of physical activity strategies based on current clinical guidelines and 6-year quality of life using observational data from 1,549 men in the Health Professionals Follow-up Study diagnosed with nonmetastatic prostate cancer between 2004-2016. Eligible individuals were free of conditions that may preclude high levels of physical activity at baseline. We estimated 6-year mean physical quality of life scores (based on EPIC-CP symptom domains; range: 1-12, lower is better) under sustained, dynamic physical activity strategies, adjusting for baseline and time-varying variables using the parametric g-formula. Estimated 6-year mean differences (adherence to physical activity recommendations vs. non-adherence) were 0.1 (95% confidence interval: 0.0,0.2) for bowel symptoms, -0.1 (-0.2,0.1) for urinary incontinence, 0.0 (-0.1,0.2) for urinary irritation/obstruction, -0.3 (-0.7,0.1) for sexual symptoms, and -0.1 (-0.2,0.1) for vitality/hormonal symptoms. Estimated 6-year mean differences comparing adherence to physical activity recommendations vs. no intervention (observed physical activity in this population) were close to zero. Adhering to current physical activity recommendations may help to improve 6-year symptoms in the sexual domain, with little expected influence on symptoms in the bowel, urinary, and vitality/hormonal domains.