Introduction: A strong association between chronic infection, inflammation, and cancer has been suggested.
Discussion: Helicobacter pylori, a microaerophilic gram negative bacterium, infects about half the world's population. It has been defined as a definitive carcinogen in the pathogenesis of gastric cancer. H. pylori evades the host immune responses and persists in the stomach leading to gastritis gastric atrophy and sometimes gastric cancer.
Conclusion: Chronic H. pylori infection causes gastric cancer via two mechanisms: the presence of virulence factors and the induction of chronic inflammation which ultimately leads to neoplastic transformation.