Polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) in ovarian cancer risk

Glutathione S-transferases (GSTs) are ubiquitous, multifunctional phase II metabolic enzymes responsible for the detoxification of estrogen involved in the development of ovarian cancer. Data from epidemiological studies show conflicting results that remain to be further clarified. We estimated in this study the genetic effects of GSTM1 and GSTT1 polymorphisms on ovarian cancer risk. Eligible studies of the two polymorphisms and ovarian cancer risk were identified from China National Knowledge Infrastructure (CNKI), PubMed, Embase, and Web of Science. We summarized all data and performed a meta-analysis. Odds ratio (OR) and 95 % CI was calculated by using the fixed effects model to estimate the associations. Eight eligible studies were finally identified providing 2,397 cases and 2,910 controls for GSTM1 polymorphism and 2,049 cases and 2,668 controls for GSTT1 polymorphism. The overall data showed that carries of the GSTM1 null genotype did not have significantly increased ovarian cancer risk compared with those who carried the GSTM1 present genotype (null vs. present-OR, 1.01; 95 % CI, 0.91-1.11; heterogeneity, P = 0.672). Similarly, for GSTT1 polymorphism, we observed no association under the investigated model in the overall analysis (null vs. present-OR, 1.02; 95 % CI, 0.89-1.17; heterogeneity, P = 0.372), and in the subgroup of Caucasian subjects (null vs. present-OR, 0.99; 95 % CI, 0.86-1.14; heterogeneity, P = 0.959). The meta-analysis does not provide a strong evidence for causal associations between GSTM1 and GSTT1 polymorphisms and risk of ovarian cancer in Caucasians.