Helicobacter pylori-induced gastric carcinogenesis

Infection is a major risk factor for cancer. A leading cause of infection-attributable cancer is the gastric pathogen, Helicobacter pylori. This bacterium, together with seven viruses and three trematode parasites, are now recognized to be group I carcinogens by the International Agency for Research on Cancer. Chronic infection with these microorganisms causes inflammation, a hallmark of cancer. H. pylori infection has become a paradigm for infectious agents that promote chronic inflammation and cancer. This chapter will provide a historical perspective on the discoveries that led to this paradigm. It will also review the bacterial, host, and environmental factors involved in H. pylori-induced gastric cancer.