Gastrointestinal Microbiota in Gastric Cancer: Potential Mechanisms and Clinical Applications—A Literature Review.

Simple Summary: The gut microbiota significantly influences gastric cancer development, with H. pylori being a primary risk factor. Other microbes also contribute through chronic inflammation, genotoxic effects, and metabolic changes. Alterations in microbiota can impact the efficacy and side effects of cancer therapies. New microbiome-targeted treatments, including dietary changes, antibiotics, probiotics, synbiotics, and fecal transplants, show potential for improving therapeutic outcomes and reducing side effects. Understanding the microbiota's role in gastric cancer could lead to more effective treatment strategies. Emerging evidence highlights the crucial role of gastrointestinal microbiota in the pathogenesis of gastric cancer. Helicobacter pylori (H. pylori) infection stands out as a primary pathogenic factor. However, interventions such as anti-H. pylori therapy, gastric surgeries, immunotherapy, and chronic inflammation significantly remodel the gastric microbiome, implicating a broader spectrum of microorganisms in cancer development. These microbial populations can modulate gastric carcinogenesis through various mechanisms, including sustained chronic inflammation, bacterial genotoxins, alterations in short-chain fatty acids, elevated gastrointestinal bile acids, impaired mucus barrier function, and increased concentrations of N-nitrosamines and lactic acid. The dynamic changes in gut microbiota also critically influence the outcomes of anti-cancer therapies by modifying drug bioavailability and metabolism, thus affecting therapeutic efficacy and side effect profiles. Additionally, the effectiveness of radiotherapy can be significantly impacted by gut microbiota alterations. Novel therapeutic strategies targeting the microbiome, such as dietary interventions, probiotic and synbiotic supplementation, and fecal microbiota transplantation, are showing promise in cancer treatment. Understanding the intricate relationship between the gut microbiota and gastric cancer is essential for developing new, evidence-based approaches to the prevention and treatment of this malignancy. [ABSTRACT FROM AUTHOR]