Helicobacter pylori infection and precancerous lesions of the stomach.

H. pylori infection is associated with a slightly increased risk of gastric cancer. However, the risk is much higher in the subgroup of infected patients who have atrophic gastritis and extensive intestinal metaplasia. In those subjects, H. pylori acts as a trigger of the sequence which begins as atrophic gastritis with intestinal metaplasia and evolves towards immature forms of intestinal metaplasia and dysplasia. It seems that factors different from H. pylori (diet, genetical background, etc.) might have an influence on how often gastric precancerous lesions appear in H. pylori-infected subjects. Effective prevention of gastric carcinoma would require identification of the patients at risk in an early step of the process. Preventive measures would include H. pylori eradication and changes in the diet (i.e., increase of vitamin C and carotenoid intake). Preliminary data suggest that H. pylori eradication cannot revert intestinal metaplasia. However, it is possible that eradication of the bacteria would prevent progression towards immature forms of intestinal metaplasia and dysplasia.