title: Genetic polymorphisms of glutathione S-transferase genes GSTM1, GSTT1 and risk of hepatocellular carcinoma.
abstract: BACKGROUND
  A number of case-control studies were conducted to investigate the association of glutathione S-transferase (GST) genetic polymorphisms and hepatocellular carcinoma (HCC) risk. However, these studies have yielded contradictory results. We therefore performed a meta-analysis to derive a more precise estimation of the association between polymorphisms on GSTM1, GSTT1 and HCC.
  PubMed, EMBASE, ISI web of science and the CNKI databases were systematically searched to identify relevant studies. Data were abstracted independently by two reviewers. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess the strength of association. Potential sources of heterogeneity were also assessed by subgroup analysis and meta-regression. Funnel plots and Egger's linear regression were used to test publication bias among the articles. A total of 34 studies including 4,463 cases and 6,857 controls were included in this meta-analysis. In a combined analysis, significantly increased HCC risks were found for null genotype of GSTM1 (OR = 1.29, 95% CI: 1.06-1.58; P = 0.01) and GSTT1 (OR = 1.43, 95% CI: 1.22-1.68; P<10(-5)). Potential sources of heterogeneity were explored by subgroup analysis and meta-regression. Significant results were found in East Asians and Indians when stratified by ethnicity; whereas no significant associations were found among Caucasians and African populations. By pooling data from 12 studies that considered combinations of GSTT1 and GSTM1 null genotypes, a statistically significant increased risk for HCC (OR = 1.88, 95% CI: 1.41-2.50; P<10(-4)) was detected for individuals with combined deletion mutations in both genes compared with positive genotypes.
  
  
  CONCLUSIONS
  This meta-analysis suggests that the GSTM1 and GSTT1 null genotype may slightly increase the risk of HCC and that interaction between unfavourable GSTs genotypes may exist.
authors.affiliation: Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai, People's Republic of China.
authors.forename: Kang
authors.initials: K
authors.lastname: Song
authors.forename: Jiayong
authors.initials: J
authors.lastname: Yi
authors.forename: Xizhong
authors.initials: X
authors.lastname: Shen
authors.forename: Yu
authors.initials: Y
authors.lastname: Cai
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000235:genetics*; D016001:Confidence Intervals; D004843:Epistasis, Genetic; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology / Q000235:genetics*; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D017594:Publication Bias; D012307:Risk Factors
chemical_list: D005982:Glutathione Transferase; C413545:glutathione S-transferase T1