Null Genotype of GSTT1 Contributes to Esophageal Cancer Risk in Asian Populations: Evidence from a Meta-analysis

Abstract

Background/Aims: Glutathione S-transferase T1 (GSTT1), a phase-II enzyme, plays an important rolein detoxification of carcinogen electrophiles. Many studies have investigated the association between GSTT1polymorphism and esophageal cancer risk in Asian populations, but its actual impact is not clear owing toapparent inconsistencies among those studies. Thus, a meta-analysis was performed to explore the effect of GSTT1polymorphism on the risk of developing esophageal cancer. <br/><b>Methods</b>: A literature search of PubMed, Embase, andWanfang databases up to August 2012 was conducted and 15 eligible papers were finally selected, involving a totalof 1,626 esophageal cancer cases and 2,216 controls. We used the pooled odds ratio (OR) with its corresponding95% confidence interval (95%CI) to estimate the association of GSTT1 polymorphism with esophageal cancerrisk. Subgroup analyses and sensitivity analyses were performed to further identify the association. <br/><b>Results</b>:Meta-analysis of total studies showed the null genotype of GSTT1 was significantly associated with an increasedrisk of esophageal cancer in Asians (OR=1.26, 95%CI=1.05-1.52, POR=0.015, I2=42.7%). Subgroup analyses bysample size and countries also identified a significant association. Sensitivity analysis further demonstrated arelationship of GSTT1 polymorphism to esophageal cancer risk in Asians. <br/><b>Conclusions</b>: The present meta-analysisof available data showed a significant association between the null genotype of GSTT1 and an increased risk ofesophageal cancer in Asians, particularly in China.