[Significance of microsatellite instability in early gastric cancer treated by endoscopic submucosal dissection]

Microsatellite instability (MSI) is defined as a change of any length due to either insertion or deletion of repeating units, in a microsatellite within a tumor when compared to normal tissue. MSI is closely related with genetic instability, particularly in hereditary nonpolyposis colorectal cancer. MSI is found in 10-50% of all gastric cancers, suggesting that MSI may play an important role in carcinogenesis. The aim of this study was to investigate the relationship between microsatellite instability and clinicopathologic features in early gastric cancers (EGCs) treated by endoscopic submucosal dissection (ESD).

We analyzed clinicopathological features of 95 specimens of EGCs including MSI, histologic type, mucin phenotype, p53, VEGF, location of cancer, depth of invasion, incidence of synchronous and metachronous cancer, age, and gender derived from 94 patients, treated by ESD during recent 19 months were analyzed in this study.

According to microsatellite stability, MSI was observed in 13 (13.7%) cases of 95 specimens. The incidence of MSI was increased in patients with cancer at lower part of stomach and female gender. There was no significant relation between MSI and clinicopathologic features including histologic type, mucin phenotype, p53, VEGF, and depth of invasion.

Our results demonstrate that there is no relationship between MSI and clinicopathologic features except tumor location and gender in ECGs treated by ESD. However, further studies are needed to evaluate the significance of MSI in EGCs.