title: Eradication of Helicobacter pylori and Gastric Cancer: A Systematic Review and Meta-analysis of Cohort Studies.
abstract: Helicobacter pylori (H. pylori) is associated with an increased risk of gastric adenocarcinoma and gastric mucosa associated lymphoid tissue (MALT) lymphoma and a decreased risk of esophageal adenocarcinoma. We aimed to assess how eradication therapy for H. pylori influences the risk of developing these cancers.
  
  
  
  This was a systematic review and meta-analysis. We searched PubMed, Web of Science, Embase, and the Cochrane Library and selected articles that examined the risk of gastric cancer, MALT lymphoma, or esophageal cancer following eradication therapy, compared with a noneradicated control group.
  
  
  
  Among 3629 articles that were considered, nine met the inclusion criteria. Of these, eight cohort studies assessed gastric cancer while one randomized trial assessed esophageal cancer. Out of 12 899 successfully eradicated patients, 119 (0.9%) developed gastric cancer, compared with 208 (1.1%) out of 18 654 noneradicated patients. The pooled relative risk of gastric cancer in all eight studies was 0.46 (95% confidence interval [CI] = 0.32 to 0.66, I(2) = 32.3%) favoring eradication therapy. The four studies adjusting for time of follow-up and confounders showed a relative risk of 0.46 (95% CI = 0.29 to 0.72, I(2) = 44.4%).
  
  
  
  This systematic review and meta-analysis indicates that eradication therapy for H. pylori prevents gastric cancer. There was insufficient literature for meta-analysis of MALT lymphoma or esophageal cancer.
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden (ED, JL, NB); Division of Cancer Studies, King's College London, London, UK (JL); Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden (LE) eva.doorakkers@ki.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Doorakkers
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden (ED, JL, NB); Division of Cancer Studies, King's College London, London, UK (JL); Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden (LE).
authors.forename: Jesper
authors.initials: J
authors.lastname: Lagergren
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden (ED, JL, NB); Division of Cancer Studies, King's College London, London, UK (JL); Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden (LE).
authors.forename: Lars
authors.initials: L
authors.lastname: Engstrand
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden (ED, JL, NB); Division of Cancer Studies, King's College London, London, UK (JL); Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden (LE).
authors.forename: Nele
authors.initials: N
authors.lastname: Brusselaers
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000517:prevention & control; D015331:Cohort Studies; D004938:Esophageal Neoplasms / Q000453:epidemiology*; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori; D006801:Humans; D018442:Lymphoma, B-Cell, Marginal Zone / Q000453:epidemiology*; D016017:Odds Ratio; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000517:prevention & control