Baseline selenium status and effects of selenium and vitamin e supplementation on prostate cancer risk

J Natl Cancer Inst. 2014 Mar;106(3):djt456. doi: 10.1093/jnci/djt456. Epub 2014 Feb 22.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • African Americans / statistics & numerical data*
  • Aged
  • Antioxidants / administration & dosage
  • Antioxidants / adverse effects*
  • Antioxidants / analysis
  • Canada / epidemiology
  • Cohort Studies
  • Dietary Supplements / adverse effects*
  • Humans
  • Male
  • Middle Aged
  • Nails / chemistry*
  • Neoplasm Grading
  • Odds Ratio
  • Proportional Hazards Models
  • Prostatic Neoplasms / chemically induced*
  • Prostatic Neoplasms / epidemiology
  • Prostatic Neoplasms / pathology
  • Puerto Rico / epidemiology
  • Randomized Controlled Trials as Topic
  • Risk
  • Selenium / administration & dosage
  • Selenium / adverse effects*
  • Selenium / analysis
  • Trace Elements / adverse effects
  • United States / epidemiology
  • Vitamin E / administration & dosage
  • Vitamin E / adverse effects*
  • Vitamin E / analysis
  • Vitamins / adverse effects

Substances

  • Antioxidants
  • Trace Elements
  • Vitamins
  • Vitamin E
  • Selenium