Genetic polymorphisms of glutathione S-transferase M1 and prostate cancer risk in Asians: a meta-analysis of 18 studies.

BACKGROUND Many studies have investigated associations between the glutathione S-transferase M1 (GSTM1) null polymorphism and risk of prostate cancer, but the impact of GSTM1 in people who live in Asian countries is still unclear owing to inconsistencies across results. METHODS We searched the PubMed, Web of Science, Scopus, Ovid and CNKI databases for studies of associations between the GSTM1 null genotype and risk of prostate cancer in people who live in Asian countries, and estimated summary odds ratios (ORs) with 95% confidence intervals (95% CIs). RESULTS A total of 18 case-control studies with 2,172 cases and 3,258 controls were included in this meta-analysis, which showed the GSTM1 null genotype to be significantly associated with increased risk of prostate cancer in people who live in Asian countries (random-effects OR=1.74, 95% CI1.44-2.09, P<0.001). Similar results were found in East Asians (OR=1.41; 95% CI: 1.12-1.78; P=0.004) and Caucasians in Asia (OR=2.19; 95% CI: 1.85-2.60; P<0.001). No evidence of publication bias was observed. CONCLUSIONS This meta- analysis of available data suggested that the GSTM1 null genotype does contribute to increased risk of prostate cancer in people who live in Asian countries.