Total Calcium (Dietary and Supplementary) Intake and Prostate Cancer: a Systematic Review and Meta-Analysis

BACKGROUND: Controversial results have been reported concerning the influence of calcium intake on prostate cancer risk. The aim of this study was to determine any association between total calcium (in the diet and in supplements) intake and prostate cancer. MATERIALS AND METHODS: The present systematic review and meta-analysis study was carried out following a PRISMA guidelines. Two reviewers independently using MeSH keywords searched international databases including PubMed, Science Direct, Cochrane, EMBASE, Web of Science, CINAHL, EBSCO and search engines such as Google Scholar. The searches were performed without any time limit until May 2016. The results were pooled using a random effects model and homogeneity was confirmed using the Q test and I(2) index. Subgroup analyses was performed according to continents and study designs. The data were analyzed using STATA software version 3.2, with p<0.05 considered significant. RESULT: Overall, 12 studies with a total sample size of 905,046 were entered into the final meta-analysis. The main age range of the participants was 50 to 70 years. The relative risks (RR) for total calcium with total prostate cancer, localized prostate cancer, and advance prostate cancer were estimated to be 1.15 (95% CI: 1.04-3.46), 1.05 (95% CI: 0.96-1.14), and 1.15 (95% CI: 0.89-1.50), respectively. Only the relationship between total calcium and total prostate cancer was significant (P<0.05). CONCLUSIONS: High calcium intake can be considered as a risk factor for total prostate cancer. Therefore, calcium intake might be a target for prevention.