Abstract:The occurrence and development of gastric cancer (GC) is determined by many factors. In recent years, the development of molecular biology has provided new ideas for the diagnosis and treatment of GC. Microsatellite instability (MSI) GC is a special type of GC caused by the body 's DNA mismatch repair (MMR) gene defect. Studies of the clinical characteristics, molecular mechanisms and prognosis of MSI GC found specific clinicopathological features and better prognosis in MSI GC compared with ordinary types of GC. However, there are still some controversies in the study of MSI gastric cancer at home and abroad. This article aims to review the concept of MSI, the relationship between MSI and clinicopathological features of gastric cancer, and the treatment progress of MSI gastric cancer.