title: Association Between Helicobacter pylori Eradication and Gastric Cancer Incidence: A Systematic Review and Meta-analysis.
abstract: Eradication of Helicobacter pylori infection has been reported to reduce the risk of gastric cancer among asymptomatic individuals in high-risk areas. The magnitude of benefit of H pylori eradication in populations with different levels of gastric cancer risk and in different clinical scenarios is unclear. We performed a systematic review and meta-analysis of randomized controlled trials and observational studies to investigate the effects of H pylori eradication on the incidence of gastric cancer.
  
  
  
  We searched PubMed, Cochrane Library, and ClinicalTrials.gov, reviewing titles and abstracts of studies of the effects of eradication of H pylori infection on risk of gastric cancer, through May 2015. We also searched bibliographies of included studies, related reviews, and abstracts presented at Digestive Disease Week. Twenty-four eligible studies (22 research manuscripts and 2 abstracts) were included in our meta-analysis (715 incident gastric cancers among a total of 48,064 individuals/340,255 person-years). We assessed the effects, as well as their modification by baseline gastric cancer incidence, study design (randomized trial vs observational study), clinical scenario (asymptomatic infected individuals vs individuals after endoscopic resection of early gastric cancer), demographic characteristics of patients (age and sex), and duration of follow-up.
  
  
  
  After adjustment for baseline gastric cancer incidence, individuals with eradication of H pylori infection had a lower incidence of gastric cancer than those who did not receive eradication therapy (pooled incidence rate ratio = 0.53; 95% confidence interval: 0.44-0.64). There was little heterogeneity among studies. Baseline gastric cancer incidence modified the benefit of H pylori eradication (P = .037 for interaction); the incidence rate ratio of gastric cancer decreased in a nonlinear fashion with increasing baseline incidence of gastric cancer (P = .018, in comparison with the linear model). The benefit also modestly increased with age (P = .023 for interaction), but this might be due to correlation between age and baseline gastric cancer incidence. Eradication provided significant benefit for asymptomatic infected individuals (pooled incidence rate ratio, 0.62; 95% CI: 0.49-0.79) and individuals after endoscopic resection of gastric cancers (pooled incidence rate ratio, 0.46; 95% CI: 0.35-0.60). The benefits of H pylori eradication did not differ with study design, sex, or follow-up period.
  
  
  
  In a systematic review and meta-analysis, we associated eradication of H pylori infection with a reduced incidence of gastric cancer. The benefits of eradication vary with baseline gastric cancer incidence, but apply to all levels of baseline risk.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Yi-Chia
authors.initials: YC
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Tsung-Hsien
authors.initials: TH
authors.lastname: Chiang
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Division of Gastroenterology and Hepatology, Chia-Yi Christian Hospital, Chia-Yi, Taiwan.
authors.forename: Chu-Kuang
authors.initials: CK
authors.lastname: Chou
authors.affiliation: Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Yu-Kang
authors.initials: YK
authors.lastname: Tu
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan. Electronic address: david.ntuh@gmail.com.
authors.forename: Wei-Chih
authors.initials: WC
authors.lastname: Liao
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Primary Care Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan. Electronic address: mingshiang@ntu.edu.tw.
authors.forename: Ming-Shiang
authors.initials: MS
authors.lastname: Wu
authors.affiliation: Department of Medicine, Michael E. DeBakey VA Medical Center, Baylor College of Medicine Houston, Texas.
authors.forename: David Y
authors.initials: DY
authors.lastname: Graham
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D016481:Helicobacter Infections / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000472:pathogenicity; D006801:Humans; D015994:Incidence; D016017:Odds Ratio; D065840:Protective Factors; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*; D018570:Risk Assessment; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D054328:Proton Pump Inhibitors
keywords: Antibiotic; Risk Factor; Stomach; Tumor