title: Risk of gastric cancer among smokers infected with Helicobacter pylori.
abstract: Infection with the gastric bacterium Helicobacter pylori (in particular infection with CagA-positive strains) and smoking have been identified as risk factors for the development of gastric cancer. Both risk factors are typically acquired early in life and prevail over decades if not for life. We assessed the individual and joint impact of both risk factors on gastric cancer risk in a population-based case-control study from Germany including 71 patients with histologically verified gastric cancer and 363 patients with colorectal cancer who served as controls. Information on smoking and potential confounding factors was collected by standardized interviews. H. pylori infection was measured serologically by immunoglobulin G antibody titers against H. pylori. In addition, antibodies against the CagA antigen were determined by Western blot. Twenty-seven percent of cases compared with 15% of controls were smokers, and 43% of cases compared with 23% of controls were infected with CagA-positive H. pylori strains. After control for potential confounders, the relative risk of gastric cancer was 2.6 (95% CI 1.2-5.7) for nonsmoking subjects with CagA-positive H. pylori infections and 7.2 (95% CI 2.2-23.6) for smoking subjects with CagA-positive H. pylori infections compared with subjects without these risk factors. The corresponding relative risks for noncardia gastric cancer were 6.1 ( 95% CI 2.3-16.5) and 16.6 (95% CI 4.3-64.2). We conclude that smoking subjects with CagA-positive H. pylori infections have a strongly increased risk of gastric cancer and may be an important group for targeting efforts of prevention and early detection.
authors.affiliation: Department of Epidemiology, German Centre for Research on Ageing, Heidelberg, Germany. brenner@dzea.uni-heidelberg.de
authors.forename: Hermann
authors.initials: H
authors.lastname: Brenner
authors.forename: Voler
authors.initials: V
authors.lastname: Arndt
authors.forename: Günter
authors.initials: G
authors.lastname: Bode
authors.forename: Christa
authors.initials: C
authors.lastname: Stegmaier
authors.forename: Hartwig
authors.initials: H
authors.lastname: Ziegler
authors.forename: Til
authors.initials: T
authors.lastname: Stümer
mesh_terms: D000230:Adenocarcinoma / Q000209:etiology* / Q000473:pathology; D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000276:immunology; D016022:Case-Control Studies; D005260:Female; D016481:Helicobacter Infections / Q000150:complications*; D016480:Helicobacter pylori / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013274:Stomach Neoplasms / Q000209:etiology* / Q000473:pathology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D007074:Immunoglobulin G; C080866:cagA protein, Helicobacter pylori