Intake of selenium in the prevention of prostate cancer: A systematic review and meta-analysis

Background: Recent studies have suggested that selenium intake may prevent the risk of developing prostate cancer. Results from some of these studies have given conflicting results. Because of these discrepant results we sought to explore the association between selenium intake and prostate cancer by conducting a systematic review and meta-analysis of the literature. Methods: We systematically searched MEDLINE, EMBASE and Cochrane Library between 1966 and May 2005 for articles that examined the association between intake of selenium and the risk of prostate cancer. We abstracted the data from relevant studies. A random effects model was used to estimate pooled relative risks for both cohort and case-control studies. Heterogeneity was assessed graphically using a Funnel Plot. Results: Sixteen studies (eleven cohort studies and five case-control studies) were included in the final analysis. The pooled relative risk of prostate cancer for any intake of selenium was 0.72 (0.61-0.84) for cohort studies and 0.74 (0.61-1.39) for case-control studies. The pooled relative risk of moderate intake was 0.74 (0.61-0.90) for cohort studies and 0.74 (0.39-1.39) for case-control studies. A dose-response trend was observed when we stratified the studies by disease severity. Conclusion: The results of our systematic review suggest that selenium intake may reduce the risk of prostate cancer. The results confirm the need for large randomized controlled trials, which are ongoing, to answer this question.