Baseline selenium status and effects of selenium and vitamin e supplementation on prostate cancer risk.
BACKGROUNDThe Selenium and Vitamin E Cancer Prevention Trial found no effect of selenium supplementation on prostate cancer (PCa) risk but a 17% increased risk from vitamin E supplementation. This case-cohort study investigates effects of selenium and vitamin E supplementation conditional upon baseline selenium status.
METHODSThere were 1739 total and 489 high-grade (Gleason 7-10) PCa cases and 3117 men in the randomly selected cohort. Proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for effects of supplementation within quintiles of baseline toenail selenium. Cox proportional hazards models were used to estimate hazard ratios, and all statistical tests are two-sided.
RESULTSToenail selenium, in the absence of supplementation, was not associated with PCa risk. Selenium supplementation (combined selenium only and selenium + vitamin E arms) had no effect among men with low selenium status (<60th percentile of toenail selenium) but increased the risk of high-grade PCa among men with higher selenium status by 91% (P = .007). Vitamin E supplementation (alone) had no effect among men with high selenium status (≥40th percentile of toenail selenium) but increased the risks of total, low-grade, and high-grade PCa among men with lower selenium status (63%, P = .02; 46%, P = .09; 111%, P = .008, respectively).
CONCLUSIONSSelenium supplementation did not benefit men with low selenium status but increased the risk of high-grade PCa among men with high selenium status. Vitamin E increased the risk of PCa among men with low selenium status. Men should avoid selenium or vitamin E supplementation at doses that exceed recommended dietary intakes.
Affiliations of authors: Cancer Prevention Program (ARK) and SWOG Statistical Center (AKD, CMT, PJG), Fred Hutchinson Cancer Research Center, Seattle, WA; Department of Epidemiology (ARK, GEG) and Department of Environmental Health (GEG), University of Washington, Seattle, WA; University of Missouri, Research Reactor Center, Columbia, MO (JSM); Harry S. Truman Memorial Veterans Hospital, Columbia, MO (JSM); Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio, TX (IMT); Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA (FLM); Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Bethesda, MD (LMM, HLP); Moores Cancer Center, University of California San Diego, San Diego, CA (SML); Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH (EAK)., , , , , , , , , ,
Proportional Hazards Models
Randomized Controlled Trials as Topic
Pub Type(s)Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't