Null genotype of glutathione S-transferase Tl contributes to colorectal cancer risk in the Asian population: a meta-analysis.

BACKGROUND AND AIM: Previous studies investigating the association between the glutathione S-transferase Tl (GSTT1) null genotype and colorectal cancer (CRC) risk in the Asian population have reported controversial results. Thus, a meta-analysis was performed to clarify the effect of the GSTT1 null genotype on CRC risk in the Asian population. METHODS: A comprehensive study was conducted, and 12 case-control studies were finally included, involving a total of 4517 CRC cases and 6607 controls. Subgroup analyses were performed by the sample size. RESULTS: A meta-analysis of all 12 studies showed that the GSTT1 null genotype was significantly associated with an increased CRC risk in the Asian population (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.02-1.19, the P-value of the OR [P(OR)] = 0.02, the value of the heterogeneity analysis [I(2)] = 42%). A more obvious association was observed after the heterogeneity was eliminated by excluding one study (OR = 1.15, 95% CI: 1.06-1.25, P(OR) = 0.001, I(2) = 0%). This association was further identified by both subgroup analyses and a sensitivity analysis. CONCLUSIONS: This meta-analysis suggests that the GSTT1 null genotype contributes to an increased colorectal cancer risk in the Asian population.