Genetic polymorphisms of glutathione S-transferase T1 and bladder cancer risk: a meta-analysis

In recent years, there have been numerous papers emphasizing the relationship between Glutathione S-transferases polymorphisms and bladder cancer risk, but the findings have not reached a consensus. The relationship between glutathione S-transferase T 1 null genotype and bladder cancer susceptibility is now even more disputable. Therefore, we present a meta-analysis of (nested) case-controlled, genotype-based studies (including 37 studies, 6,986 cases and 9,166 controls) examining this association. Using a fixed-effect model, statistically significant increase was observed between glutathione S-transferase T 1 deletion and bladder cancer risk for the overall studies (OR = 1.12; 95% confidence interval (CI): 1.04-1.21; P = 0.004 for Z test; I (2) = 47.43 for heterogeneity). After adjusting the result using trim-and-fill method, the outcome still had significant difference with little downgrade (OR = 1.10, 95% CI = 1.02-1.18). Three potential sources of heterogeneity including ethnicity, source of control and smoking status were also assessed. Minor increased correlation was found only in population-based studies (OR = 1.16; 95% CI = 1.03-1.30; I (2) = 47.16). Our analysis suggests that glutathione S-transferase T 1 null status is associated with a modest increase in the risk of bladder cancer and the difference exiting in source of control has been confirmed. Due to limited sample size, various confounding variables as well as discrepancy in study design, a valid conclusion still cannot be confirmed.