Gene–environment interactions on the risk of esophageal cancer among Asian populations with the G48A polymorphism in the alcohol dehydrogenase-2 gene: a meta-analysis

The aim of this study is to investigate the gene–environment interactions between the G48A polymorphism in the alcohol dehydrogenase-2 ( ADH2 ) gene and environmental factors in determining the risk of esophageal cancer (EC). A literature search was conducted in the PubMed, Embase, Web of Science, Cochrane Library, and Google Scholar databases to indentify eligible studies published before November 1, 2013. We performed a meta-analysis of 18 case–control studies with a total of 8,906 EC patients and 13,712 controls. The overall analysis suggested that individuals with the GG genotype were associated with a 2.77-fold increased risk of EC, compared with carriers of the GA and AA genotypes. In a stratified analysis by ethnic group, Japanese, Mainland Chinese, and Taiwan Chinese with the GG genotype had a significantly higher risk of EC, compared with Thai and Iranian populations, indicating ethnic variance in EC susceptibility. An analysis of combined effect indicated that GG genotype of ADH2 G48A was associated with the highest risk of EC in heavy drinkers and smokers. A striking difference was found to exist between males and females, showing gender variance for the association between ADH2 G48A and EC risk. This meta-analysis shows that the GG genotype of ADH2 G48A may be associated with an increased risk of EC in Asian populations. In addition, significant gene–environment interactions were found. Heavy drinkers, smokers, and males with the GG genotype may have a higher EC risk. Thus, our results shed new light on the complex gene–environment interactions that exist between environmental factors and ADH2 G48A polymorphism in EC risk.