title: Baseline selenium status and effects of selenium and vitamin e supplementation on prostate cancer risk.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  There 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.
  
  
  RESULTS
  Toenail 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).
  
  
  CONCLUSIONS
  Selenium 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.
authors.affiliation: 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).
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kristal
authors.forename: Amy K
authors.initials: AK
authors.lastname: Darke
authors.forename: J Steven
authors.initials: JS
authors.lastname: Morris
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Tangen
authors.forename: Phyllis J
authors.initials: PJ
authors.lastname: Goodman
authors.forename: Ian M
authors.initials: IM
authors.lastname: Thompson
authors.forename: Frank L
authors.initials: FL
authors.lastname: Meyskens
authors.forename: Gary E
authors.initials: GE
authors.lastname: Goodman
authors.forename: Lori M
authors.initials: LM
authors.lastname: Minasian
authors.forename: Howard L
authors.initials: HL
authors.lastname: Parnes
authors.forename: Scott M
authors.initials: SM
authors.lastname: Lippman
authors.forename: Eric A
authors.initials: EA
authors.lastname: Klein
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D019587:Dietary Supplements / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009262:Nails / Q000737:chemistry*; D060787:Neoplasm Grading; D016017:Odds Ratio; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000139:chemically induced* / Q000453:epidemiology / Q000473:pathology; D011647:Puerto Rico / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D012643:Selenium / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis; D014131:Trace Elements / Q000009:adverse effects; D014481:United States / Q000453:epidemiology; D014810:Vitamin E / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis; D014815:Vitamins / Q000009:adverse effects
chemical_list: D000975:Antioxidants; D014131:Trace Elements; D014815:Vitamins; D014810:Vitamin E; D012643:Selenium