Relationship between Helicobacter pylori gastritis, gastric cancer and gastric acid secretion

Epidemiological evidence strongly indicates that Helicobacter pylori infection is an essential factor for the development of most non-cardia gastric cancer. Furthermore, the identification of an effective animal model and a plausible biological hypothesis provide further compelling evidence for its pathogenic role. Nevertheless, it will be some years before prospective studies in humans are able to confirm cause and effect beyond any doubt. In the meantime sceptics point out that the prevalence of Helicobacter pylori in different countries do not always correlate with the incidence of gastric cancer. It is unclear why patients with duodenal ulcer (who are almost invariably infected) are protected from the disease. Cancer often develops in patients from whom Helicobacter disappeared from the stomach years previously. This paper discusses the relationship between Helicobacter pylori infection, the development of gastritis and its evolution to non-cardia gastric cancer. It also addresses possible reasons why the incidence of gastric cancer does not always mirror the prevalence of Helicobacter infection throughout the world and why patients with duodenal ulcer may be protected from developing gastric cancer.