[Helicobacter pylori and malignant diseases of the stomach].

The association between Helicobacter pylori infection and gastric malignancies, cancer and MALT lymphoma, has been suggested through several lines of evidence during the last decade. Although unresolved issues still cast doubts on the real weight of these association, in the sequence of events that leads to gastric cancer or lymphoma, Helicobacter pylori appears to play a prominent role in the very initial steps as causative agent of chronic gastritis. The subsequent events in the sequence--atrophy, intestinal metaplasia, dysplasia and cancer are multifactorial involving environmental agents, host response and characteristics of the bacterial strain itself. Recognition of the causal role of Helicobacter pylori infection in the cancer induction theoretically presents tools for its prevention. The ongoing studies will show in the future whether eradication or prevention of infection are followed by a reduction in risk of cancer. Lymphomas arising from gastric mucosa-associated lymphoid tissue (MALT) may be a clonal evolution starting from the infection. In low-grade gastric MALT lymphoma cure of the infection induces complete remission in the majority of patients. Longer follow-up investigations are necessary to determine if remissions indicate a cure of the disease.