Gastric microbiota in gastric cancer and precancerous stages: Mechanisms of carcinogenesis and clinical value.

Gastric cancer (GC) is a globally important disease. The discovery of Helicobacter pylori (H. pylori) demonstrated that the human stomach is not a sterile environment, and recent advances in molecular biology have led to the detection of large populations of microorganisms in the stomach. A growing number of studies have elucidated differences in the microbiota of patients at various stages of GC development. Evidence from insulin-gastrin transgenic (INS-GAS) and human gastric microbiota-transplanted mouse models have further demonstrated the potential causality of microbiota in the development of GC. To date, H. pylori is still thought to be the strongest risk factor for GC. H. pylori interacts with non-H. pylori commensals and affects the composition of the gastric microbiota. This review provides an overview of the relationship between the gastric microbiota and GC, including the mechanisms of microbe-associated carcinogenesis, the clinical value of the microbiota as a GC biomarker, and the potential of modulating the microbiota for GC prevention or therapy.