title: Glutathione S-transferase M1 gene polymorphism and gastric cancer risk: an updated analysis.
abstract: OBJECTIVE
  Studies investigating the association between glutathione S-transferase M1 (GSTM1) gene polymorphism and gastric cancer (GC) risk have reported conflicting results. In order to clarify the effect of GSTM1 genotype on the GC risk, we performed an updated meta-analysis of published case-control and cohort studies to better compare results between studies.
  
  
  METHODS
  Published literature from PubMed, EMBASE, and China National Knowledge Infrastructure (CNKI) were retrieved, and the literature search was updated on June 15, 2010. 49 studies with 7746 cases of GC and 13,230 controls were selected. A fixed- or random-effects model was used to calculate pooled effect estimates depending on statistical heterogeneity.
  
  
  RESULTS
  The combined analyses showed that there was a significant difference in genotype distribution between GC cases and controls among Asians, but not among Caucasians. Stratified analyses according to control sources also showed the positive association between GSTM1 null genotype and increased risk of GC. However, smoking and Helicobacter pylori infection did not modify the association between this polymorphism and GC susceptibility (p = 0.56 and 0.31, respectively). When stratifying by the location, Lauren's classification, and histological differentiation of GC, we observed no statistically significant differences in genotype distribution. A strong correlation between increased GC risk and the combined GSTM1 and GSTT1 null genotype was observed.
  
  
  CONCLUSIONS
  This meta-analysis demonstrated that the GSTM1 gene polymorphism might be a risk factor for GC among Asians (especially, in some Eastern countries). Smoking, Helicobacter pylori infection status did not modify the association between GSTM1 null genotype and GC risk.
authors.affiliation: Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, 37 Guo Xue Road, Chengdu, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Ping
authors.initials: P
authors.lastname: Yang
authors.forename: Xiao-ting
authors.initials: XT
authors.lastname: Wu
mesh_terms: D044466:Asian People / Q000235:genetics; D002681:China; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics*; D016481:Helicobacter Infections; D006801:Humans; D011110:Polymorphism, Genetic; D039781:PubMed; D012307:Risk Factors; D012907:Smoking; D013274:Stomach Neoplasms / Q000201:enzymology* / Q000235:genetics*
chemical_list: D005982:Glutathione Transferase