Plasma selenium level before diagnosis and the risk of prostate cancer development

Purpose: Epidemiological studies and a randomized intervention trial sugges t that the risk of prostate cancer may be reduced by selenium intake. We in vestigated whether plasma selenium level before diagnosis correlated with t he risk of later developing prostate cancer. Materials and Methods: A case control study was performed on men from the B altimore Longitudinal Study of Aging registry, including 52 with known pros tate cancer and 96 age matched controls with no detectable prostatic diseas e. Plasma selenium was measured at an average time plus or minus standard d eviation of 3.83 +/- 1.85 years before the diagnosis of prostate cancer by graphite furnace atomic absorption spectrophotometry. Adjusted odds ratio a nd 95% confidence interval were computed with logistic regression. Results: After correcting for years before diagnosis, body mass index, and smoking and alcohol use history, higher selenium was associated with a lowe r risk of prostate cancer. Compared with the lowest quartile of selenium (r ange 8.2 to 10.7 mug./dl.), the odds ratios of the second (10.8 to 11.8), t hird (11.9 to 13.2) and fourth (13.3 to 18.2) quartiles were 0.15 (95% conf idence interval 0.05 to 0.50), 0.21 (0.07 to 0.68) and 0.24 (0.08 to 0.77, respectively, p =0.01). Furthermore, plasma selenium decreased significantl y with patient age (p <0.001). Conclusions: Low plasma selenium is associated with a 4 to 5-fold increased risk of prostate cancer. These results support the hypothesis that supplem ental selenium may reduce the risk of prostate cancer. Because plasma selen ium decreases with patient age, supplementation may be particularly benefic ial to older men.