Lack of association between vitamin D receptor gene FokI and BsmI polymorphisms and prostate cancer risk: an updated meta-analysis involving 21,756 subjects

The vitamin D receptor (VDR) is a crucial mediator for the cellular effects of vitamin D. The polymorphisms in the VDR gene have been hypothesized to alter the risk of prostate cancer. However, studies investigating the association between VDR polymorphisms (BsmI and FokI) and prostate cancer (PCa) risk report conflicting results , therefore, we conducted a meta-analysis to re-examine the controversy. Published literatures from PubMed, Embase, Google Scholar, and China National Knowledge Infrastructure (CNKI) were searched (updated to March 9, 2013). According to our inclusion criteria, studies that observed the association between VDR BsmI and FokI polymorphisms and PCa risk were included. The principal outcome measure was the odds ratio (OR) with 95 % confidence interval (CI) for PCa risk associated with VDR BsmI and FokI polymorphisms. Thirty-four studies involving 10,267 cases and 11,489 controls were recruited. Overall, we did not find evidence to support an association between any of the VDR polymorphisms and PCa risk. For BsmI, the pooled OR was 0.894 (95 % CI 0.773 to 1.034) for the Bb vs. bb genotypes, 1.002 (95 % CI 0.869 to 1.157) for the BB vs. bb genotypes, 0.922 (95 % CI 0.798 to 1.065) for the dominant model (BB/Bb vs. bb), and 1.018 (95 % CI 0.936 to 1.107) for the recessive model (BB vs. Bb/bb). ORs for the FokI polymorphisms were similar. The results suggest that the VDR BsmI and FokI polymorphisms are not related to PCa risk. Further large and well-designed studies are required to confirm this conclusion.