Selenium Supplementation, Baseline Plasma Selenium Status and Incidence of Prostate Cancer: An Analysis of the Complete Treatment Period of the Nutritional Prevention of Cancer Trial

BJU Int. 2003 May;91(7):608-12. doi: 10.1046/j.1464-410x.2003.04167.x.

Abstract

Objective: To present the results (to January 1996, the end of blinded treatment) of the Nutritional Prevention of Cancer (NPC) Trial, a randomized trial of selenium (200 micro g daily) designed to test the hypothesis that selenium supplementation (SS) could reduce the risk of recurrent nonmelanoma skin cancer among 1312 residents of the Eastern USA.

Materials and methods: Original secondary analyses of the NPC to 1993 showed striking inverse associations between SS and prostate cancer incidence. A subsequent report revealed that this effect was accentuated among men with the lowest baseline plasma selenium concentrations. The effects of treatment overall and within subgroups of baseline prostate-specific antigen (PSA) and plasma selenium concentrations were examined using incidence rate ratios and Cox proportional hazards models.

Results: SS continued to significantly reduce the overall incidence (relative risk and 95% confidence interval) of prostate cancer (0.51, 0.29-0.87). The protective effect of SS appeared to be confined to those with a baseline PSA level of <or= 4 ng/mL (0.35, 0.13-0.87), although the interaction of baseline PSA and treatment was not statistically significant. Participants with baseline plasma selenium concentrations only in the lowest two tertiles (< 123.2 ng/mL) had significant reductions in prostate cancer incidence. A significant interaction between baseline plasma selenium and treatment was detected.

Conclusion: To the end of the blinded treatment the NPC trial continued to show a significant protective effect of SS on the overall incidence of prostate cancer, although the effect was restricted to those with lower baseline PSA and plasma selenium concentrations.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biopsy / methods
  • Dietary Supplements*
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Prostate-Specific Antigen / blood
  • Prostatic Neoplasms / blood
  • Prostatic Neoplasms / diet therapy*
  • Prostatic Neoplasms / epidemiology
  • Retrospective Studies
  • Selenium / administration & dosage
  • Selenium / blood*

Substances

  • Prostate-Specific Antigen
  • Selenium