Prognostic significance of high microsatellite instability in a Spanish series of gastric adenocarcinomas

In colorectal cancer different levels of microsatellite instability (MSI) have been described MSI-H (high) characterizes a unique clinical and pathological phenotype known as hereditary non-polyposis colorectal cancer syndrome, whereas MSI-L (low) and MSS (stable) are considered similar phenotypes without pathological implications. MSI has been also described as a frequent genetic alteration in a subset of gastric adenocarcinomas. However, the clinicopathological and prognosis significance of this abnormality in these tumors remains unclear: To investigate the role of genetic instability in gastric carcinogenesis we examined 10 microsatellite loci in 37 patients. MSI-H was found in 37.8% patients. We observed a trend of MSI-H tumors to be associated with elderly patients, intestinal histological type, advanced clinical stages and less aggressiveness with better survival. In conclusion, MSI-H can be considered as a good prognosis factor in a subset of gastric tumors.