Role Of "Oncobacteria" In Oncogenesis: Selected Examples

Helicobacter pylori plays a particular role among "oncobacteria" and was recognized by IARC as a group I carcinogen. In the stomach of humans and animals, it induces two histologically distinct types of tumors: adenocarcinoma (epithelial tumor) and B-cell lymphoma (mesenchymal tumor), which never occur simultaneously in the same individual. An attempt was made at explaining this phenomenon on the basis of the mutual relationship between the host and the bacteria (Fig. 1).