Abstract
Widespread microsatellite instability (MSI) occurs in nearly 15% of sporadic colorectal cancers. Large bowel carcinomas with high‐frequency MSI (MSI‐H) (instability at > or = 30% of microsatellite loci) are believed to display distinctive pathologic features and to behave less aggressively than microsatellite‐stable (MSS) tumors and carcinomas with low‐frequency MSI (MSI‐L) (instability at < 30% of microsatellite loci). In this study we would like to show the impression of MSI on clinical condition and outcome of patients with colorectal adenocarcinoma.
Methods: MSI status was evaluated in 600 large bowel adenocarcinomas using polymerase chain reaction (PCR) and sequencing. Tumors that showed instability with at least two microsatellite markers were classified as MSI‐H, whereas the other tumors were classified as MSI‐L (instability at one locus) or MSS (no instability).
Results: MSI‐H was detected in 51.6% of CRC patients. The prevalence of proximal lesions in the MSI‐H group (38.7%) was higher than in the MSS group (27.4%). The percentage of moderately differentiated tumors was slightly lower in the MSI‐H group (16.3%) when compared to the MSS group. Eight mutations were detected in five patients with 32 MSI‐H.
Conclusion: Assessment of MSI status is an essential step in discovering genetic characterizations of large bowel carcinomas and identifies a subset of tumors with distinct clinical, pathologic, and biologic features.
Citation Information: Cancer Prev Res 2010;3(1 Suppl):A87.
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