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

Background/Aims: Studies of associations between genetic polymorphism of glutathione S-transferase T1 (GSTT1) and risk of colorectal cancer (CRC) in Asian populations have reported controversial results. Thus, a meta-analysis was performed to clarify the effects of GSTT1 polymorphism on the risk of developing colorectal cancer.
Methods: A literature search of PubMed and EMBASE up to June 7, 2011 was conducted and 13 eligible papers were finally selected, involving totals of 4,832 CRC cases and 7,045 controls. Subgroup analyses were performed according to the sample size and the research designwith the software programs Review Manager (version 5.0.10) and STATA (version 9.2).
Results: Analyses of all relevant studies showed an increased CRC risk was significantly associated with the null genotypes of GSTT1 (OR=1.09, 95%CI=1.01-1.17, POR=0.027; I2=40.2%). Besides, a more obvious association was observed after heterogeneity was eliminated (OR=1.13, 95%CI 1.04-1.23, POR=0.002; I2=0.0%). Subgroup analyses and sensitivity analysis further identified an association in Asians.
Conclusions: This meta-analysis demonstrated the GSTT1 null genotype to be associated with an increased risk of CRC in Asian populations.