0281 Risk of Bladder Cancer Among Men Reporting Nocturia in the Cancer Prevention Study-II Nutrition Cohort

Abstract Introduction Bladder cancer is one of the five most common cancers in men; however, few risk factors have been identified. The ‘urogenous contact’ hypothesis states that prolonged contact of the urothelium to carcinogens can lead to mutations that induce cancer. Poor sleep health has been associated with increased risk of several cancers, including bladder cancer. Nocturia, the interruption of sleep to urinate, may, in part, explain the relationship between sleep and cancer. Several studies on nocturia and bladder cancer have been conducted but relied on retrospective assessment of nocturia, which may be impacted by recall bias. We sought to evaluate the relationship between nocturia and bladder cancer risk in a prospective cohort. Methods The Cancer Prevention Study-II Nutrition Cohort is a population-based study of cancer incidence initiated in 1992. Follow-up surveys were mailed to participants biennially starting in 1997. Nocturia was assessed in men in 1997 and 2003. We stratified models by smoking status (never, former, current) and adjusted for age, education, body mass index, physical activity, hypertension, and use of diuretics. Participants were followed until their last survey, cancer diagnosis, or death. Exposures were updated in 2003. We used a Cox proportional hazards model to calculate hazard ratios (HR) and 95% confidence intervals (95%CI) for the association between nocturia and bladder cancer. Results Among 49,767 men, there were 1,207 bladder cancer cases over a median 15.0 years follow-up. Among current smokers, nocturia frequency of 1/night was associated with decreased bladder cancer risk (HR 0.51, 95%CI 0.28, 0.92), but not 2+/night (HR 0.89, 95%CI 0.50, 1.57). Among former smokers, there was elevated, though not statistically significant, risk of bladder cancer associated with nocturia (HR 1/night 1.18, 95%CI 0.92, 1.51; HR 2+/night 1.13, 95%CI 0.88, 1.45). There were no significant associations among non-smokers. Conclusion Among smokers, 1 occasion of nocturia may be protective against bladder cancer, suggesting strategies to reduce contact of the urothelium to carcinogens may help reduce cancer risk in this population. Support (if any) The American Cancer Society funds the creation, maintenance, and updating of the Cancer Prevention Study-II cohort. This analysis was also supported through an unrestricted research grant from Sleep Number Corporation.