Association of vitamin D receptor polymorphisms with colorectal cancer susceptibility: A systematic meta-analysis

Recent studies have reported an association between vitamin D receptor (VDR) polymorphisms and colorectal cancer (CRC) risk; however, the results are controversial. This meta-analysis was performed to investigate whether the Cdx-2, Tru9I, FokI, BsmI, TaqI, and ApaI polymorphisms were correlated with CRC susceptibility. METHODS: All potential studies were retrieved by searching the PubMed, EMBASE, and Cochrane Library databases through October 2, 2021. Odds ratios (ORs) with 95% confidence intervals were used to evaluate the correlation between VDR gene Cdx-2, Tru9I, FokI, BsmI, TaqI, and ApaI polymorphisms and CRC risk. RESULTS: In this meta-analysis, the BsmI variant was significantly correlated with a lower risk of CRC, especially in Caucasian population (B vs b: OR 0.94, 95%CI 0.90–0.99; BB vs bb: OR 0.88; 95%CI 0.79–0.97; BB vs Bb/bb: BB vs Bb/bb: OR 0.89; 95%CI 0.81–0.98). A statistically significant result from the FokI polymorphism was observed in colon cancer rather than rectal cancer (Ff vs FF: OR 0.86, 95%CI 0.84–0.93; ff/Ff vs FF: OR 0.88, 95%CI 0.79–0.98; ff vs Ff/FF: OR 0.90, 95%CI 0.82–0.99). Similarly, Cdx-2 polymorphism was found to be associated with decreased CRC risk among Africans (C vs c: OR 0.50, 95%CI 0.33–0.75; CC vs cc: OR 0.09, 95%CI 0.01–0.77; Cc vs cc: OR 0.49, 95%CI 0.30–0.81; CC/Cc vs cc: OR 0.45, 95%CI 0.28–0.74,). CONCLUSION: Our findings indicate that VDR polymorphisms are significantly associated with CRC risk.