Genetic polymorphisms of vitamin D receptor and the risk of prostate cancer: a meta-analysis.

PURPOSE Vitamin D receptor (VDR) polymorphisms are considered to be risk factors for prostate cancer. However, previous case-control studies on the association between the variants of VDR and prostate cancer have shown contradictory results. Therefore, the role of VDR in prostate cancer remains unresolved. To investigate a potential correlation between VDR polymorphisms and prostate cancer risk, a meta-analysis of case-control and cohort studies was conducted. METHODS Eligible studies were retrieved via both computerized searches and review of references. The association of VDR polymorphisms to prostate cancer was evaluated for 4 well-known VDR polymorphisms (FokI, BsmI, ApaI and TaqI) separately. Stratified analyses on ethnic characteristics (Caucasians or Asians), cancer stage (localized or advanced) and Gleason score (<7 or >>7) were performed. Fixed- or random-effect models were used to summarize the estimates of odds ratio (OR) with 95%CI according to the heterogeneity. Sensitivity analyses were conducted. RESULTS A total of 40 studies met the inclusion criteria of the meta-analysis. The FF genotype illustrated a protective effect on prostate cancer in the Caucasian subgroup (OR=0.905, 95%CI 0.823, 0.995). Conversely, the bb and the TT genotypes were associated with increased risk of prostate cancer (OR=0.838, 95%CI 0.709,0.990; OR=1.127, 95%CI 1.023,1.242, respectively). CONCLUSION Our analysis supported the hypothesis that several different VDR polymorphisms may increase the risk of prostate cancer. However, others illustrated a protective effect on carcinogenesis. Further efforts should be made to establish the mechanisms between VDR polymorphisms and prostate cancer.