Individual and joint contribution of family history and Helicobacter pylori infection to the risk of gastric carcinoma

BACKGROUND. Helicobacter pylori infection and a positive family history of gastric carcinoma have: been identified as risk factors for the disease. It is unclear, however, to what degree their impact on the risk of gastric ca rcinoma is independent, because H. pylori also clusters within families. METHODS. The authors carried out a population-based, statewide case-control study in Saarland, Germany, to assess the individual and joint contributio ns of family history and PI. pylori infection to the risk of gastric carcin oma. Cases included 68 patients with histologically verified gastric carcin oma. Controls included 239 patients with colorectal carcinoma who were matc hed to the cases by age and gender. Information on family history (defined as gastric carcinoma in at least one first-degree relative) and potential c onfounders was collected by standardized interviews. Immunoglobulin G antib odies against H, pylori were measured by enzyme-linked immunosorbent assay. In addition, antibodies against the CagA antigen were determined by Wester n blot analysis. RESULTS. H. pylori infection and family history were positively related, an d both risk factors were more common among cases than among controls. Altho ugh the association between family history and gastric carcinoma was somewh at reduced fry control for a pylori infection, both risk factors still show ed strong independent relations with gastric carcinoma after control for ea ch other. Compared with uninfected subjects who had no family history, subj ects with both a positive family history and infection with a CagA positive H. pylori strain had a more than 8-fold total risk of gastric carcinoma (a djusted odds ratio [QR], 8.2; 95% confidence interval [CI], 2.2-30.4) and a 16-fold risk of noncardia gastric carcinoma(OR 16.0; 95% CI, 3.9-66.4). CONCLUSIONS, Infection with CagA positive H.pylori strains and a positive f amily history appear to he strong independent risk factors for gastric carc inoma. They may be useful markers for identifying subjects at high risk for the disease and for targeting efforts of prevention and early detection. ( C) 2000 American Cancer Society.