Hebicobacter pylori infection and risk of cardia cancer and non-cardia gastric cancer - A nested case-control study

Background: Helicobacter pylori infection is an established risk factor for gastric adenocarcinoma. Potential confounding by socioeconomic factors has not been adequately assessed, and the magnitude of the relative risk in re lation to gastric subsites, morphologic subtypes, sex, age, and follow-up t ime need further study. Methods: We conducted a serologic case-control stud y nested within the Norwegian JANUS cohort. Between 1972 and 1986 serum was collected from 101,601 subjects who were followed up with regard to cancer development through 1992. Results: Among 208 gastric adenocarcinoma cases, we found a strong positive association between H. pylori infection and non -cardia gastric cancer (odds ratio (OR), 5.15; 95% confidence interval (CI) , 2.83-9.37), and a statistically significant negative association with car dia cancer (OR, 0.40; 95% CI, 0.20-0.77). Adjustment for socioeconomic fact ors and smoking did not materially alter the effect estimates. The associat ion between the infection and non-cardia cancer was stronger for tumors dis tal to the angulus and tended to be stronger in women than in men. The resu lts were similar across Lauren morphologic subtypes. Conclusions: These res ults strengthen the evidence of H. pylori infection as a risk factor in non -cardia gastric cancer. A negative association with H. pylori infection was found for cardia cancer.