Gut Microbiota and Gastric Cancer: The Immunoregulatory Mechanism and the Preventive Role of Microbiota‐Derived Short‐Chain Fatty Acids

Gastric cancer is still a major worldwide health problem, and its etiology is attributed to several factors, including the composition of the gut microbiota and its immunomodulatory functions. The present review discusses the complex interrelationship between the gut microbiota metabolites, especially short‐chain fatty acids (SCFAs) and the onset of gastric cancer. Dysbiosis of the gut microbiota, reduced diversity of microbial species, and increased relative abundance of certain bacterial taxa have been found to contribute to the progression of gastric cancer and its treatment. For instance, Helicobacter pylori is still considered a well‐recognized cause; nevertheless, other bacteria, such as Enterobacteriaceae and Prevotella , have emerged as putative gastric cancer causative agents in recent investigations. In addition, SCFAs, particularly butyrate, produced in the gut are known to modulate immune functions by enhancing the cytotoxic activity of CD8+ T cells and preventing gastric cancer, possibly via the GPR109A receptor. Although research on the cause–effect relationship between microbiota and gastric cancer is an emerging field, available data from human and animal studies suggest that the manipulation of the gut microbiota—through probiotics, diet, or specific treatments—may be useful in preventing and managing gastric cancer. This review discusses the role of gut microbiota and SCFAs in the diagnosis and therapy of gastric cancer, with a focus on their effective application in gastric cancer treatment.