Microsatellite instability in colorectal adenomas: relevance and clinical importance.

A number of investigations have recently been published on the role of microsatellite instability (MSI) in the process of colorectal carcinogenesis. The data concerning colorectal adenomas are difficult to compare (due to differences in the tumor collection, selection and number of analyzed loci, definition of high and low instability and histological types), and this review therefore examines the significance of the results of these publications. We then discuss the extent to which MSI and its effects on the integrity of the genome are early or late events in the malignant transformation, and which clinicopathological features are presented by MSI-positive adenomas. Finally, we consider the clinical importance of microsatellite status for the diagnosis of hereditary nonpolyposis colorectal cancer and the possibility of preventing adenomas and carcinomas by nonsteroidal anti-inflammatory drugs.