Association between microsomal epoxide hydrolase 1 polymorphisms and susceptibility to esophageal cancer: a meta-analysis

Microsomal epoxide hydrolase 1 (EPHX1) plays an important role in the detoxification of carcinogenic polycyclic aromatic hydrocarbons. EPHX1 Tyr113His and His139Arg polymorphisms have been reported to have some impacts on the EPHX1 activity. Previous case–control studies assessing the associations between EPHX1 polymorphisms and esophageal cancer risk reported conflicting results. To quantitatively summarize the associations of EPHX1 Tyr113His and His139Arg polymorphisms with esophageal cancer risk, a systemic review and meta-analysis of published studies were performed. Published literatures from PubMed, Embase, and China National Knowledge Infrastructure databases were searched. The strength of the associations between EPHX1 polymorphisms and esophageal cancer risk was estimated by the pooled odds ratios (ORs) with its 95 % confidence interval (95 %CI). This meta-analysis yielded nine case–control studies, which included nine studies for Tyr113His polymorphism (1,291 cases and 2,120 controls) and seven studies for His139Arg polymorphism (899 cases and 1,615 controls). Overall, meta-analysis showed that EPHX1 Tyr113His polymorphism was not associated with esophageal cancer risk under all genetic models. Meta-analysis of these seven studies for EPHX1 His139Arg polymorphism showed that EPHX1 His139Arg polymorphism was also not associated with esophageal cancer risk under all genetic models. However, subgroup analysis by ethnicity further showed that there was an obvious association between EPHX1 His139Arg polymorphism and decreased risk of esophageal cancer in Caucasians (ArgArg versus HisArg/HisHis: OR = 0.52, 95 %CI 0.27–0.97, P = 0.041). This meta-analysis suggests that EPHX1 His139Arg polymorphism is associated with decreased risk of esophageal cancer in Caucasians. In addition, more studies with large samples are needed to get a more precise estimation on the associations mentioned above.