Physical Activity, Diet Quality, and Risk of Prostate Cancer Grade Reclassification on Active Surveillance: Results from a Prospective Cohort Study

Background Higher diet quality may be associated with a reduced risk of prostate cancer (PCa) grade reclassification (GR) on active surveillance (AS). However, there remain limited and conflicting data regarding whether physical activity may influence disease progression. Methods This is a prospective cohort study of men with Grade Group (GG) 1 PCa enrolled in AS. Patients completed detailed diet and physical activity surveys at time of AS enrollment. Physical activity was evaluated as metabolic equivalent of task (MET) hours per week, diet quality was measured as energy-adjusted Healthy Eating Index (E-HEI) score. Multivariable competing risk regressions were utilized to examine the association of diet and physical activity with GR on biopsy to ≥ GG2 or ≥ GG3. Results We included 828 men with a median follow up of 6.4 years. We found no significant association between MET hours per week and GR to ≥ GG2 (subdistribution hazard ratio (SHR) 1.04 per standard deviation (SD) increase in weekly MET hours, 95% confidence interval (CI) 0.90–1.21), or extreme GR to ≥ GG3 (SHR 1.03, 95% CI 0.79–1.35). Higher overall diet quality remained associated with significantly reduced risks of GR to ≥ GG2 (SHR 0.85 per SD increase in E-HEI score, 95% CI 0.73–0.99) and extreme GR (SHR 0.74, 95% CI 0.58–0.95). Conclusions In this prospective cohort study with longitudinal follow-up of men diagnosed with GG1 PCa pursuing AS, after adjusting for clinicopathological and lifestyle factors, increasing physical activity was not associated with a lower risk of PCa GR. A higher overall diet quality was associated with a reduced risk of GR for both GR outcomes. In our cohort, physical activity level does not appear to be associated with PCa progression on AS.