The relationship between gastric cancer frequency and the ratio of gastric to duodenal ulcer.

An international comparison of the ratio of mortality rates from gastric and duodenal ulcers (GU/DU) reveals a positive correlation with gastric carcinoma death rates. This correlation is driven by the rates of gastric ulcer and has decreased in recent decades. Genetic susceptibility factors appear to be involved in the pathogenesis of peptic ulcers: non-secretor phenotypes of blood groups predispose to both types of peptic ulcers, while blood group A predominates in gastric ulcer and group O in duodenal ulcers. Environmental factors such as smoking increase the risk for both types of ulcers while excessive salt intake increases the risk of gastric ulcer only. Such aetiological factors may modulate the outcome of Helicobacter pylori infection. Factors associated with duodenal ulcer lead to a non-atrophic diffuse antral gastritis while those associated with gastric ulcer lead to multifocal atrophic gastritis. The latter, but not the former, type of gastritis provides a micro-environmental favouring neoplastic transformation of the gastric epithelium.