Helicobacter pylori is the dominant species in the human gastric microbiome and causes persistent inflammation, which is the strongest risk factor for gastric cancer. However, only a small proportion of infected individuals develop malignancy. The risk is influenced by bacterial strains, host responses, and interactions between host and microbe. Understanding these factors is crucial for prevention and mechanistic insights into inflammatory carcinomas. Gastric adenocarcinoma is the second leading cause of cancer-related death globally, with high mortality rates. Two histological variants exist: diffuse-type, which affects younger individuals, and intestinal-type, which progresses through stages of inflammation and metaplasia. H. pylori colonizes gastric epithelium and is the most common bacterial infection worldwide. It causes gastritis, which persists for decades, leading to a dynamic equilibrium between the organism and host. However, this relationship incurs biological costs. H. pylori infection is the strongest known risk factor for gastric cancer, with approximately 75% attributable risk. While it increases the risk of both diffuse and intestinal-type gastric adenocarcinoma, chronic inflammation is not required for diffuse-type cancers, suggesting different mechanisms. Eradication of H. pylori reduces cancer risk, emphasizing its role in early carcinogenesis. However, only a small proportion of colonized individuals develop neoplasia, involving complex interactions between pathogen and host. Chronic superficial gastritis is an early step in the progression to intestinal-type gastric cancer, characterized by inflammatory cell infiltration. Atrophic gastritis is an intermediate step, marked by gland loss and inflammatory cell encroachment. H. pylori strains are genetically diverse, with variations in vacA sequences linked to gastric malignancy. VacA induces vacuolation and apoptosis in gastric epithelial cells, and its effects on immune responses facilitate long-term colonization. H. pylori's outer membrane proteins, such as BabA and SabA, bind to host antigens and are associated with increased gastric cancer risk. OipA, another OMP, influences disease outcomes by regulating pro-inflammatory cytokines. Phase variation allows H. pylori to evade the host immune system by altering surface proteins. The cag pathogenicity island enhances the risk of distal gastric cancer. CagA is translocated into host cells, where it activates β-catenin signaling, contributing to carcinogenesis. CagA also interacts with integrins, promoting cell migration and altering cell polarity. β-catenin activation is crucial in H. pylori-induced carcinogenesis, with evidence linking it to gastric cancer progression. EGFR transactivation by H. pylori increases β-catenin activity, promoting cell proliferation and reducing apoptosis. This contributes to pre-malignant changes and gastric cancer development. Inflammation, particularly chronic gastritis, promotes epithelial hyperproliferation and aberrant differentiation through Wnt-mediated pathways, linking inflammation and β-catenin signaling in gastric carcinHelicobacter pylori is the dominant species in the human gastric microbiome and causes persistent inflammation, which is the strongest risk factor for gastric cancer. However, only a small proportion of infected individuals develop malignancy. The risk is influenced by bacterial strains, host responses, and interactions between host and microbe. Understanding these factors is crucial for prevention and mechanistic insights into inflammatory carcinomas. Gastric adenocarcinoma is the second leading cause of cancer-related death globally, with high mortality rates. Two histological variants exist: diffuse-type, which affects younger individuals, and intestinal-type, which progresses through stages of inflammation and metaplasia. H. pylori colonizes gastric epithelium and is the most common bacterial infection worldwide. It causes gastritis, which persists for decades, leading to a dynamic equilibrium between the organism and host. However, this relationship incurs biological costs. H. pylori infection is the strongest known risk factor for gastric cancer, with approximately 75% attributable risk. While it increases the risk of both diffuse and intestinal-type gastric adenocarcinoma, chronic inflammation is not required for diffuse-type cancers, suggesting different mechanisms. Eradication of H. pylori reduces cancer risk, emphasizing its role in early carcinogenesis. However, only a small proportion of colonized individuals develop neoplasia, involving complex interactions between pathogen and host. Chronic superficial gastritis is an early step in the progression to intestinal-type gastric cancer, characterized by inflammatory cell infiltration. Atrophic gastritis is an intermediate step, marked by gland loss and inflammatory cell encroachment. H. pylori strains are genetically diverse, with variations in vacA sequences linked to gastric malignancy. VacA induces vacuolation and apoptosis in gastric epithelial cells, and its effects on immune responses facilitate long-term colonization. H. pylori's outer membrane proteins, such as BabA and SabA, bind to host antigens and are associated with increased gastric cancer risk. OipA, another OMP, influences disease outcomes by regulating pro-inflammatory cytokines. Phase variation allows H. pylori to evade the host immune system by altering surface proteins. The cag pathogenicity island enhances the risk of distal gastric cancer. CagA is translocated into host cells, where it activates β-catenin signaling, contributing to carcinogenesis. CagA also interacts with integrins, promoting cell migration and altering cell polarity. β-catenin activation is crucial in H. pylori-induced carcinogenesis, with evidence linking it to gastric cancer progression. EGFR transactivation by H. pylori increases β-catenin activity, promoting cell proliferation and reducing apoptosis. This contributes to pre-malignant changes and gastric cancer development. Inflammation, particularly chronic gastritis, promotes epithelial hyperproliferation and aberrant differentiation through Wnt-mediated pathways, linking inflammation and β-catenin signaling in gastric carcin