Microsatellite instability as a tool for the classification of gastric cancer

Microsatellite instability (MSI) is a com mon feature of gastric cancers th at reflects underlying mismatch-repair deficiency in the tumor, caused most frequently by methylation of the hMLH1 promoter, Tumors with MSI have been found to inactivate certain target genes by permitting an increased freque ncy of mutations in mononucleotide runs in their coding regions. Gastric tu mors with MSI have a distinct clinicopathological profile with a relatively good prognosis. Using the simple and robust methodologies available, MSI d etection in gastrointestinal tumors promises to be one of the first widely used molecular prognostic tests for human cancer. Here, we review the molec ular context of this exciting prospect with respect to one of the world's m ost prevalent cancers, that of the stomach.