CHEMIOPREVENTION OF PROSTATE CANCER WITH ANTIOXIDANT VITAMINS


A large controlled clinical trial from Canada. BACKGROUND AND OBJECTIVE. Randomized trials have shown that supplementation with selenium or vitamin E is associated with a reduction of prostate cancer risk. We assessed whether a supplementation with low doses of antioxidant vitamins and minerals could reduce the occurrence of prostate cancer and influence biochemical markers. EXPERIMENTAL. The SU.VI.MAX trial comprised 5,141 men randomised to take either a placebo or a supplementation with nutritional doses of vitamin C, vitamin E, beta-carotene, selenium and zinc daily for 8 years. Biochemical markers of prostate cancer risk such as prostate-specific antigen (PSA) and insulin-like growth factors (IGFs) were measured on plasma samples collected at enrolment and at the end of follow-up from 3,616 men. Cox regression models were used to estimate the hazard ratio and related 95% confidence interval of prostate cancer associated with the supplementation and to examine whether the effect differed among predetermined susceptible subgroups. FINDINGS. During the follow-up, 103 cases of prostate cancer were diagnosed. Overall, there was a moderate, non significant reduction in prostate cancer rate associated with the supplementation (hazard ratio = 0.88; 95% CI = 0.60 ? 1.29). However, the effect differed significantly between men with normal baseline PSA (< ng/L) and those with elevated PSA (p=0.009). Among men with normal PSA, there was a marked, statistically significant reduction in the rate of prostate cancer for men receiving the supplements (hazard ratio = 0.52; 95% CI = 0.29-0.92). In men with elevated PSA at baseline, the supplementation was associated with an increased incidence of prostate cancer of borderline statistical significance (hazard ratio = 1.54; 95% CI = 0.87-2.72). The supplementation had no effect on PSA or IGF levels. SIGNIFICANCE. The findings support the hypothesis that chemoprevention of prostate cancer can be achieved with nutritional doses of antioxidant vitamins and minerals. Meyer et al (2005) Antioxidant vitamin and mineral supplementation and prostate cancer prevention in the SU.VI.MAX trial
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Source: Nutrafoods, 2005 – Volume 4 No.4