Physical Activity and Bladder Cancer Risk: Findings of the Japan Collaborative Cohort Study

Abstract

Purpose The association of physical activity with the risk of bladder cancer remains inconsistent among Asian populations. We aimed to examine the association in a large Japanese cohort. Materials and Methods In a population-based prospective cohort study, a total of 50,374 Japanese adults aged 40-79 years without a history of cancer or cardiovascular disease who had information on physical activity from self-administrated questionnaires were used for analysis. We performed Cox proportional hazard models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for incident bladder cancer after adjusting for several potential confounders. Results During the median 17.5 years of follow-up, 153 incident bladder cancers (116 men and 37 women) were identified. After the multivariable adjustment, HRs (95% CI) of bladder cancer concerning those with recreational sports participation of 1-2 hr/wk, 3-4 hr/wk, and 5 hr/wk and more were 0.67 (0.38-1.20), 0.79 (0.36-1.74), and 0.28 (0.09-0.89), respectively (p for trend=0.017). Compared with mostly sitting at the workplace, occupational physical activity of standing and walking were associated with a lower risk of bladder cancer (HR, 0.53 [95% CI, 0.32 to 0.85]). Hours of daily walking were not associated with the risk. The lower risk of bladder cancer was more evident for recreational sports (HR, 0.33 [95% CI, 0.10 to 1.00]), and for occupational standing and walking activity at work (HR, 0.57 [95% CI, 0.33 to 0.98]) among men. Conclusion Recreational sports participation and occupational physical activity were inversely associated with the risk of bladder cancer among Japanese, especially in men.