Vitamin D receptor FokI polymorphism and the risks of colorectal cancer, inflammatory bowel disease, and colorectal adenoma

Based on an inverse association between vitamin D levels and the risks of colorectal diseases, a functional start codon polymorphism in the vitamin D receptor (VDR) gene is speculated to affect the risks for these diseases. To validate this hypothesis, we first conducted a case-control study of 695 colorectal cancer patients and 1,397 controls. The association of VDR FokI polymorphism with colorectal cancer risk was analyzed using a logistic regression model. In the present case-control study, compared to the F allele, the f allele seemed to be associated with lower risks of colon cancer and advanced colorectal cancer. Additionally, a meta-analysis of 27 studies was conducted to combine findings from previous studies investigating the association of FokI polymorphism with colorectal disease using a random effects model. In the present meta-analysis, the f allele was positively associated with the risk of inflammatory bowel disease, including Crohn's disease and ulcerative colitis. However, this allele was inversely associated with colon cancer and was not associated with the risk of rectal cancer or colorectal adenoma. In conclusion, the findings from this study imply that the role of VDR FokI polymorphism may differ based on the type and severity of colorectal disease.