Helicobacter pylori and gastric cancer: the causal relationship.

Gastric cancer has been recognized as an important cause of morbidity and mortality all over the world. Helicobacter pylori has been shown to have a causal relationship to gastric cancer. The knowledge into the mechanisms related to this has advanced considerably over the last few years thereby unarguably defining the role of this host-pathogen interaction. Epidemiological studies, research in animal models, molecular pathways involving host and bacterial factors, environmental factors and recent work on stem cells have contributed to understanding the origin and progress of this neoplasia. These form part of the myriad of interplaying factors resulting in the causal relationship. Nevertheless, current evidence is insufficient to accurately identify a definitive population where prevention or treatment strategies have to be targeted. Future trials will have to define the people at risk and shed more light in these areas.