Associations between α-tocopherol, β-carotene, and retinol and prostate cancer survival

Abstract

Previous studies suggest that carotenoids and tocopherols (vitamin E compounds) may be inversely associated with prostate cancer risk, yet little is known about how they affect prostate cancer progression and survival. We investigated whether serum α-tocopherol, β-carotene, and retinol concentrations, or the α-tocopherol and β-carotene trial supplementation, affected survival of men diagnosed with prostate cancer during the α-Tocopherol, β-Carotene Cancer Prevention Study, a randomized, double-blind, placebocontrolled primary prevention trial testing the effects of β-carotene and α-tocopherol supplements on cancer incidence in adult male smokers in southwestern Finland (n = 29,133). Prostate cancer survival was examined using the Kaplan-Meier method with deaths from other causes treated as censoring, and using Cox proportional hazards regression models with hazard ratios (HR) and 95% confidence intervals (CI) adjusted for family history of prostate cancer, age at randomization, benign prostatic hyperplasia, age and stage at diagnosis, height, body mass index, and serum cholesterol. As of April 2005, 1,891 men were diagnosed with prostate cancer and 395 died of their disease. Higher serum A-tocopherol at baseline was associated with improved prostate cancer survival (HR, 0.67; 95% CI, 0.45-1.00), especially among cases who had received the α-tocopherol intervention of the trial and who were in the highest quintile of α-tocopherol at baseline (HR, 0.51; 95% CI, 0.20-0.90) or at the 3-year follow-up measurement (HR, 0.26; 95% CI, 0.09-0.71). Serum β-carotene, serum retinol, and supplemental β-carotene had no apparent effects on survival. These findings suggest that higher α-tocopherol (and not β-carotene or retinol) status increases overall prostate cancer survival. Further investigations, possibly including randomized studies, are needed to confirm this observation. © 2009 American Association for Cancer Research.