A literature review and systematic meta-analysis on Thr241Met polymorphism associating with susceptibility of oral cancer.

Oral cancer is very common, occurring on head as well as neck region with poor prognosis. The X-ray repair cross-complementing group 3 gene contained in DNA repairing pathway has been investigated for its functional role in oral cancer. Nevertheless, the corresponding results are inconclusive. This study investigated the association of Thr241Met polymorphism regarding oral cancer risk. Article and literature searches were performed using Embase, Medline, PubMed, Wanfang and China National Knowledge Infrastructure (CNKI) databases with a manual search. The keywords of ' or X-ray repair cross complementing protein 3', 'polymorphism or SNP', 'oral cancer or oral squamous cell carcinoma' and their combinations were used to search literature. In accordance with the criteria of inclusion, we focused on only case-and-control studies with the distribution of genotypes and alleles being available to be extracted. Systematic meta-analysis was conducted via the STATA software (version 11.0). After a comprehensive literature collection and review, 1,615 oral cancer cases and 1,897 matched controls extracted from 7 articles were included for this meta-analysis. Our results show that only Met/Met (TT) genotype with the recessive model was associated with high risk of oral cancer (CC + CT vs. TT, OR=1.81, P=0.001, 95% CI=1.28-2.567). A significant relationship was identified under both homozygous and recessive model in Asians (CC vs. TT: OR=2.15, 95% CI=1.107-4.170, P=0.024; CT + CC vs. TT: OR=2.140, 95% CI=1.105-4.144, P=0.024), but not among Caucasians (P>0.05). The results indicate that 241Met allele might be a potential factor for oral cancer risk, particularly among Asian population. A further study using a larger population and more ethnicities should be performed to confirm the findings.