[Intestinal metaplasia, dysplasia, gastric cancer and Helicobacter pylori: epidemiological observations]

Gastric cancer (GC) is the world's second leading cause of cancer-related mortality, and carries a bad prognosis. In 1994, Helicobacter pylori (H. pylori) has been classified by the International Agency for Research on Cancer as a group I carcinogen. There are increasing indications that this infection is associated with both the initiation and progress of gastric carcinoma and lymphoma. Evidence supporting a causal association has been demonstrated by epidemiological data and in experimental animal models. Despite this, there is still lack of final conclusion regarding the association between the infection and the malignancy due both to marked geographic variations and heterogeneity in study designs. Given the high rate of morbidity and mortality associated with GC, any means of reducing the occurrence of the disease or increase its early detection is most desirable. In this paper, the epidemiological aspects on the evidence of a causal relationship between H. pylori and GC are discussed. Prospective cohort studies and interventional trials focused on the effects of H. pylori eradication on lesions predisposing to GC should be performed in order to provide further data.