Background: Epidemiologic evidence indicates that greater intakes of vitamin D may decrease the risk of colorectal cancer. Variants in the vitamin D receptor (VDR) gene have the potential to modify associations between vitamin D intake and colorectal cancer. Methods: Associations between intakes of vitamin D and colorectal cancer were studied in a large case-control study conducted in central and northeastern Pennsylvania including 1,012 cases with histologically confirmed colorectal cancer and 1,080 population-based controls. Associations between 35 tag SNPs encompassing the VDR gene and risk for colorectal cancer as well as gene-diet associations were also assessed among a subset of the population (770 controls, 710 cases). Results: No significant trends were observed between vitamin D intake and colorectal cancer risk. After adjustment for multiple comparisons, none of the SNPs or haplotypes within the VDR gene were associated with colorectal cancer. There were also no interactions between dietary factors and variants in the entire VDR gene. Conclusions: Overall, results from this study suggest that vitamin D intake and variants in the VDR gene have little effect on risk for colorectal cancer. Impact: Increasing vitamin D intake from the diet may not result in decreasing the incidence of colorectal cancer.
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