Background Antioxidant micronutrients may affect the development and progression of prostate cancer. We conducted a pooled analysis of the associations of the concentrations of several antioxidant biomarkers with risk of prostate cancer death in the Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group.

Methods Principal investigators of prospective studies provided individual participant data for prostate cancer cases and controls on circulating concentrations of carotenoids, retinol, and tocopherols, and blood and toenail selenium, including a total of 12 biomarkers. Data were available for up to 1196 prostate cancer deaths and 2441 controls from up to 13 studies. Risk by study-specific fifths of each biomarker was estimated using multivariable-adjusted conditional logistic regression in matched case-control sets.

Results Carotenoids, retinol and tocopherols were not significantly related to risk of prostate cancer death. The only statistically significant finding was an inverse association between toenail selenium concentrations and risk of prostate cancer death (OR for the highest compared with the lowest fifth 0.37, 95% CI 0.26–0.52, the median time of follow-up from blood collection to death from prostate cancer for cases was 11.8 years); however, circulating selenium concentrations were not associated with risk (OR for highest fifth 0.94, 0.64–1.38).

Conclusion Although we found that men with higher concentrations of toenail selenium had a lower risk of dying from prostate cancer, this should be interpreted cautiously due to the inconsistency between the results for toenail and blood measures of selenium.

Acknowledgements We thank the collaborating studies (ATBC, CARET, CLUE I, CLUE II, EPIC-Europe, EPIC-Norfolk, FMC, HPFS, MCCS, MEC, NLCS, PHS, and PLCO) and participants.

On behalf of the Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group (EHNBPCCG).