Helicobacter pylori (H. pylori) is a major cause of gastric adenocarcinoma, but only a small fraction of infected individuals develop cancer. The risk of cancer is influenced by H. pylori strain differences, host genetic factors, and interactions between the host and the bacteria. H. pylori induces chronic gastritis, which can progress to atrophic gastritis, intestinal metaplasia, dysplasia, and finally adenocarcinoma. The development of gastric cancer is associated with H. pylori strains that have specific genetic features, such as the cag island, which enhances inflammatory responses and promotes carcinogenesis. H. pylori also affects host immune responses, including the production of cytokines like IL-1β and TNF-α, which can influence gastric acid secretion and contribute to cancer risk. Host genetic polymorphisms, such as those affecting IL-1β and TNF-α, also play a role in determining cancer risk. H. pylori can induce apoptosis in gastric epithelial cells, which may influence cancer development. The interaction between H. pylori and the host is dynamic, with the host's immune response affecting bacterial growth and vice versa. H. pylori eradication can reduce the risk of gastric cancer, as shown by clinical studies. Additionally, H. pylori may have a protective effect against other cancers, such as oesophageal adenocarcinoma, by reducing the risk of GERD and its complications. The relationship between H. pylori and gastric cancer is complex, involving multiple genetic and environmental factors. Understanding these interactions is crucial for developing targeted therapies and diagnostics for gastric cancer.Helicobacter pylori (H. pylori) is a major cause of gastric adenocarcinoma, but only a small fraction of infected individuals develop cancer. The risk of cancer is influenced by H. pylori strain differences, host genetic factors, and interactions between the host and the bacteria. H. pylori induces chronic gastritis, which can progress to atrophic gastritis, intestinal metaplasia, dysplasia, and finally adenocarcinoma. The development of gastric cancer is associated with H. pylori strains that have specific genetic features, such as the cag island, which enhances inflammatory responses and promotes carcinogenesis. H. pylori also affects host immune responses, including the production of cytokines like IL-1β and TNF-α, which can influence gastric acid secretion and contribute to cancer risk. Host genetic polymorphisms, such as those affecting IL-1β and TNF-α, also play a role in determining cancer risk. H. pylori can induce apoptosis in gastric epithelial cells, which may influence cancer development. The interaction between H. pylori and the host is dynamic, with the host's immune response affecting bacterial growth and vice versa. H. pylori eradication can reduce the risk of gastric cancer, as shown by clinical studies. Additionally, H. pylori may have a protective effect against other cancers, such as oesophageal adenocarcinoma, by reducing the risk of GERD and its complications. The relationship between H. pylori and gastric cancer is complex, involving multiple genetic and environmental factors. Understanding these interactions is crucial for developing targeted therapies and diagnostics for gastric cancer.