Is Helicobacter pylori infection a necessary condition for noncardia gastric cancer?

Although the association between Helicobacter pylori infection and gastric cancer is well established, this association might have been underestimated in epidemiologic studies because of possible clearance of the infection in the course of disease development. The authors addressed this hypothesis in a case-control study from Saarland, Germany (68 cases first diagnosed between 1996 and 1998 and 360 controls), with serologic assessment of H. pylori infection in which various exclusion criteria were used to minimize potential bias from this source. Joint application of three such exclusion criteria (blood sample taken more than 90 days after gastrectomy, advanced (T4) gastric cancer, and CagA positivity in Western blot analysis despite a negative result in anti-H. pylori immunoglobulin G enzyme-linked immunosorbent assay) increased the odds ratio of noncardia gastric cancer from 3.7 (95% confidence interval (CI): 1.7, 7.9) to 18.3 (95% CI: 2.4, 136.7) for any H. pylori infection and from 5.7 (95% CI: 2.6, 12.8) to 28.4 (95% CI: 3.7, 217.1) for CagA-positive H. pylori infections. Furthermore, there was no single H. pylori-negative patient out of 32 patients with noncardia gastric cancer left after additional exclusion of subjects with borderline levels in immunoglobulin G enzyme-linked immunosorbent assay. The H. pylori-gastric cancer relation may be much stronger than previously thought, and H. pylori infection may even be a (close to) necessary condition for development of noncardia gastric cancer.