title: Helicobacter pylori infection and gastric lymphoma.
abstract: BACKGROUND
  Helicobacter pylori infection is a risk factor for gastric adenocarcinoma. We examined whether this infection is also a risk factor for primary gastric non-Hodgkin's lymphoma.
  
  
  METHODS
  This nested case-control study involved two large cohorts (230,593 participants). Serum had been collected from cohort members and stored, and all subjects were followed for cancer. Thirty-three patients with gastric non-Hodgkin's lymphoma were identified, and each was matched to four controls according to cohort, age, sex, and date of serum collection. For comparison, 31 patients with nongastric non-Hodgkin's lymphoma from one of the cohorts were evaluated, each of whom had been previously matched to 2 controls. Pathological reports and specimens were reviewed to confirm the histologic type of the tumor. Serum samples from all subjects were tested for H. pylori IgG by an enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Thirty-three cases of gastric non-Hodgkin's lymphoma occurred a median of 14 years after serum collection. Patients with gastric lymphoma were significantly more likely than matched controls to have evidence of previous H. pylori infection (matched odds ratio, 6.3; 95 percent confidence interval, 2.0 to 19.9). The results were similar in both cohorts. Among the 31 patients with nongastric lymphoma, a median of six years had elapsed between serum collection and the development of disease. No association was found between nongastric non-Hodgkin's lymphoma and previous H. pylori infection (matched odds ratio, 1.2; 95 percent confidence interval, 0.5 to 3.0).
  
  
  CONCLUSIONS
  Non-Hodgkin's lymphoma affecting the stomach, but not other sites, is associated with previous H. pylori infection. A causative role for the organism is plausible, but remains unproved.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Calif.
authors.forename: J
authors.initials: J
authors.lastname: Parsonnet
authors.forename: S
authors.initials: S
authors.lastname: Hansen
authors.forename: L
authors.initials: L
authors.lastname: Rodriguez
authors.forename: A B
authors.initials: AB
authors.lastname: Gelb
authors.forename: R A
authors.initials: RA
authors.lastname: Warnke
authors.forename: E
authors.initials: E
authors.lastname: Jellum
authors.forename: N
authors.initials: N
authors.lastname: Orentreich
authors.forename: J H
authors.initials: JH
authors.lastname: Vogelman
authors.forename: G D
authors.initials: GD
authors.lastname: Friedman
mesh_terms: D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D016481:Helicobacter Infections / Q000150:complications* / Q000175:diagnosis; D016480:Helicobacter pylori / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008228:Lymphoma, Non-Hodgkin / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000209:etiology*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G