Background: Published data regarding the association between GSTM1 and/or GSTT1 gene polymorphisms and esophageal cancer (EC) susceptibility remain inconclusive. To clarify these associations, a meta-analysis was conducted.
Methods: We conducted a comprehensive search in PubMed, Embase, and the China National Knowledge Infrastructure (CNKI) for all such manuscripts published as of May 1, 2017. The pooled odds ratio (ORs) with confidence intervals (95% CI) were estimated for each study to assess the strength of the association. A subgroup analysis, a sensitivity analysis, and a publication bias analysis were also performed.
Results: Data from 41 studies comprising 5291 EC cases and 8191 controls were available for analysis of the GSTM1 polymorphism, and data from 31 studies comprising 4330 EC cases and 6558 controls were available for analysis of the GSTT1 polymorphism. Analyses of the GSTM1 polymorphisms demonstrated that there was a significantly increased EC risk in GSTM1 null genotype carriers (OR = 1.319, 95% CI = 1.125-1.546, p for heterogeneity <0.001). In subgroup analyses by ethnicity, and categories of EC, a significantly increased EC risk was found in Asians (OR = 1.457, 95% CI = 1.212-1.751, p for heterogeneity <0.001) and patients whose histological type was unknown. Analyses of the GSTT1 polymorphisms indicated a positive correlation between the GSTT1 null genotype and the EC risk (OR = 1.233, 95% CI = 1.044-1.455, p for heterogeneity <0.001). In subgroup analyses stratified by ethnicity and categories of EC, similar statistical associations were observed in Asians, esophageal squamous cell carcinoma (ESCC) patients, and ESCC on Asian population. In the GSTM1-GSTT1 interaction analysis, we discovered remarkably enhanced EC risk for patients with the GSTM1 and GSTT1 dual null genotypes (OR = 1.962, 95% CI = 1.178-3.268, p for heterogeneity <0.001) compared with the reference GSTM1 and GSTT1 dual positive genotype.
Conclusions: We conclude that the GSTM1 and GSTT1 null genotypes are associated with increased genetic susceptibility to EC in the overall human population, particularly among Asians. In addition, our findings suggest that persons with a null genotype for both the GSTM1 and GSTT1 genes are at higher risk of developing EC. Further well-designed studies are needed to confirm these associations.
Keywords: GSTM1; GSTT1; esophageal cancer; meta-analysis; polymorphism.