Vitamin D gene pathway polymorphisms and risk of colorectal, breast, and prostate cancer

Higher vitamin D exposure is hypothesized to prevent several cancers, possibly through genomic effects modulated by the vitamin D receptor (VDR), and autocrine/paracrine metabolism of the VDR's ligand, 1alpha,25-(OH)(2)-vitamin D. Herein we review the background and evidence to date on associations between polymorphisms in VDR and selected genes in the vitamin D pathway in relation to colorectal, breast, and prostate cancer. Although most studies to date have examined only a few VDR polymorphisms, more are beginning to comprehensively investigate polymorphisms in the VDR as well as in other vitamin D pathway genes, such as the vitamin D-binding protein gene (Gc) and CYP27B1 and CYP24A1, which code for enzymes that, respectively, synthesize and degrade 1alpha,25-(OH)(2)-vitamin D. Currently, there is no strong, consistent epidemiologic evidence for substantial influences of single variants in vitamin D pathway genes on risk for colorectal, breast, or prostate cancer, but promising leads are developing.