HELICOBACTER-PYLORI INFECTION AND GASTRIC LYMPHOMA

Background, Helicobacter pylori infection is a risk factor for gastric adenocarcinoma. We examined whether this infection is also a risk fac tor for primary gastric non-Hodgkin's lymphoma. Methods. This nested c ase-control study involved two large cohorts (230,593 participants). S erum had been collected from cohort members and stored, and all subjec ts were followed for cancer. Thirty-three patients with gastric non-Ho dgkin's lymphoma were identified, and each was matched to four control s according to cohort, age, sex, and date of serum collection. For com parison, 31 patients with nongastric non-Hodgkin's lymphoma from one o f the cohorts were evaluated, each of whom had ;been previously matche d to 2 controls. Pathological reports and specimens were reviewed to c onfirm the histologic type of the tumor. Serum samples from all subjec ts were tested for H. pylori IgG by an enzyme-linked immunosorbent ass ay. Results. Thirty-three cases of gastric non-Hodgkin's lymphoma occu rred a median of 14 years after serum collection. Patients with gastri c lymphoma were significantly more likely than matched controls to hav e evidence of previous H. pylori infection (matched odds ratio, 6.3; 9 5 percent confidence interval, 2.0 to 19.9). The results were similar in both cohorts. Among the 31 patients with nongastric lymphoma, 8 med ian of six years had elapsed between serum collection and the developm ent of disease. No association was found between nongastric non-Hodgki n's lymphoma and previous H. pylori infection (matched odds ratio, 1.2 ; 95 percent confidence interval, 0.5 to 3.0). Conclusions. Non-Hodgki n'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.