Helicobacter infection, chronic inflammation, and the development of malignancy.

Chronic infection with Helicobacter pylori affects approximately half the world and results in malignancy in a small subset of this population. Although the frequency of infection in developed nations is falling with a resultant decline in H. pylori-associated peptic ulcer disease, gastric cancer remains the second major cause of cancer death worldwide, with H. pylori infection being a major attributable factor in the development of gastric cancer. This review provides an update on the pathogenesis of Helicobacter infection, the malignancies associated with infection, and how infection and chronic inflammation may lead to the development of gastric malignancy, emphasizing recent developments in the field, particularly those published in leading journals. Recent studies have broadened our understanding of the pathogenesis of chronic inflammation associated with Helicobacter infection, and how chronic inflammation contributes to carcinogenesis. There is also continuing evidence from eradication studies in humans and animal models to support the association of Helicobacter infection with gastric cancer. Although there are some differences in the various human trials, recent studies support the notion that early eradication of infection may prevent the development of malignancy, but once certain events have taken place, the process leading to cancer may not be reversible. Continued research into bacterial and host factors that are associated with an increased risk of the development of gastric cancer have also enhanced our understanding of this field. The emerging literature has important implications for the understanding of the basic pathophysiology leading to malignancy in chronic H. pylori infection throughout the world. Treatment of infection may be beneficial in preventing the development of cancer in certain settings, and the role of antioxidants and other approaches is promising but requires further study. Findings from the investigation of host and bacterial factors that may predispose to the development of more severe disease manifestations including gastric cancer are also important developments in this area.