Infectious agents and gastric tumours. An increasing role for Epstein-Barr virus.

Helicobacter pylori (H. pylori) and Epstein-Barr virus (EBV) are 2 common and widely disseminated agents throughout the world. H. pylori has been classified, by the International Agency for Research on Cancer conference, as a class I carcinogen, i.e. undoubted cause of gastric cancer. However, this infection does not explain all the epidemiological and histological variations of the malignancies affecting the stomach. EBV has been identified, in the last decade, in the tumour cells of patients with gastric carcinoma and recent findings suggest the possibility of distinct mechanisms in its pathogenesis. A prevalent role of the virus has been described in a subset of stomach cancers, namely lymphoepithelioma-like carcinomas. The present update attempts to focus on the epidemiological evidence and the biological plausibility for a causal role of H.pylori and EBV infection in the pathogenesis of gastric cancer.