There is growing evidence that factors associated with circadian rhythm disruption may be associated with prostate cancer risk. In a previous analysis focusing on shift-work in the Cancer Prevention Study (CPS)-II that included only employed men, we observed an association between short sleep duration and higher risk of prostate cancer death that was limited to the first eight years of follow-up of the cohort. To corroborate and expand on these results, we examined the association between sleep duration and death from prostate cancer in a combined analysis of men in CPS-II and men enrolled in an earlier cohort study, CPS-I, regardless of employment status. After excluding men with uninterpretable sleep information, prevalent cancer and prevalent prostate disease at baseline, the analysis included 407,649 men from CPS-I followed from 1950 through 1972, and 416,040 men from CPS-II followed from 1982 through 2012. During follow-up, 1,546 men in CPS-I and 8,704 men in CPS-II died of prostate cancer. Cox proportional hazards regression was used to estimate multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI) and estimates were meta-analyzed using a fixed-effects model because the design and population of CPS-I and CPS-II were similar. Among men aged 65 years and younger, short sleep duration was associated with higher risk of death from prostate cancer during the first eight years of follow-up; compared to 7 hours/night, the RRs (95% CIs) for 3-5, and 6 hours/night were 1.61 (1.10-2.37), and 1.25 (0.99-1.58), respectively. Among men older than age 65 years, the corresponding RRs (95% CIs) were 0.97 (0.68, 1.38), and 1.02 (0.82, 1.27), respectively. There was no association between sleep duration and fatal prostate cancer during later follow-up. These findings support evidence that factors related to circadian rhythms may increase fatal prostate cancer risk. The observed association between short sleep duration and higher risk of fatal prostate cancer only during the first 8-years of follow-up suggests that short sleep duration could affect later stages of prostate carcinogenesis. Reasons for lack of an association in older men are unclear but may include the marked decline in nocturnal melatonin levels with age, which could reduce the relative biologic impact of melatonin inhibition by sleep-deprivation.

Citation Format: Susan M. Gapstur, Victoria L. Stevens, Brian D. Carter, Ying Wang, Eric J. Jacobs. Sleep duration and risk of fatal prostate cancer in CPS-I and CPS-II [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2306. doi:10.1158/1538-7445.AM2017-2306