title: Epstein-Barr Virus and Gastric Cancer Risk: A Meta-analysis With Meta-regression of Case-control Studies.
abstract: OBJECTIVE
  Research on how the risk of gastric cancer increases with Epstein-Barr virus (EBV) infection is lacking. In a systematic review that investigated studies published until September 2014, the authors did not calculate the summary odds ratio (SOR) due to heterogeneity across studies. Therefore, we include here additional studies published until October 2015 and conduct a meta-analysis with meta-regression that controls for the heterogeneity among studies.
  
  
  METHODS
  Using the studies selected in the previously published systematic review, we formulated lists of references, cited articles, and related articles provided by PubMed. From the lists, only case-control studies that detected EBV in tissue samples were selected. In order to control for the heterogeneity among studies, subgroup analysis and meta-regression were performed.
  
  
  RESULTS
  In the 33 case-control results with adjacent non-cancer tissue, the total number of test samples in the case and control groups was 5280 and 4962, respectively. In the 14 case-control results with normal tissue, the total number of test samples in case and control groups was 1393 and 945, respectively. Upon meta-regression, the type of control tissue was found to be a statistically significant variable with regard to heterogeneity. When the control tissue was normal tissue of healthy individuals, the SOR was 3.41 (95% CI, 1.78 to 6.51; I-squared, 65.5%).
  
  
  CONCLUSIONS
  The results of the present study support the argument that EBV infection increases the risk of gastric cancer. In the future, age-matched and sex-matched case-control studies should be conducted.
authors.affiliation: Department of Preventive Medicine, Jeju National University School of Medicine, Jeju, Korea.
authors.forename: Jong-Myon
authors.identifier: 0000-0003-3080-7852
authors.initials: JM
authors.lastname: Bae
authors.affiliation: Department of Preventive Medicine, Jeju National University School of Medicine, Jeju, Korea.
authors.forename: Eun Hee
authors.identifier: 0000-0002-1065-1080
authors.initials: EH
authors.lastname: Kim
mesh_terms: D016022:Case-Control Studies; D004279:DNA, Viral / Q000032:analysis / Q000378:metabolism; D016208:Databases, Factual; D020031:Epstein-Barr Virus Infections / Q000473:pathology* / Q000821:virology; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D006801:Humans; D016017:Odds Ratio; D013274:Stomach Neoplasms / Q000473:pathology* / Q000821:virology
chemical_list: D004279:DNA, Viral
keywords: Epstein-Barr virus; Gastric neoplasms; Meta-analysis; Risk factor