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

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 hours/week, 3-4 hours/week, and 5 hours/week 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: 0.32-0.85]). 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, 1.00]), and for occupational standing and walking activity at work (HR: 0.57 [95% CI: 0.33, 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.