Background: Two distinct genetic mutational pathways characterized by either chromosomal instability or high-frequency microsatellite instability (MSI-H) are currently recognized in the pathogenesis of colorectal cancer (CRC). Recently, it has been shown that patients with primary CRC that displays MSI-H have a significant, stage-independent, multivariate survival advantage. Untreated CRC hepatic metastases are incurable and are associated with a median survival of 4 to 12 months. Conversely, surgical resection in selected patients results in a 20% to 50% cure rate. The aim of this study was to investigate the prognostic importance of MSI-H in patients undergoing resection of hepatic CRC metastases.
Methods: DNA was extracted from paraffin-embedded, resected metastatic CRC liver lesions and corresponding normal liver parenchyma from 190 patients. MSI-H status was determined by polymerase chain reaction–based evaluation of the noncoding mononucleotide repeats BAT-25 and BAT-26.
Results: MSI was detected in tumors from 5 (2.7%) of the 190 CRC patients. All MSI-H tumors were in patients with node-positive CRC primary tumors. The median survival after hepatic resection of MSI-H and non–MSI-H tumors was 67 and 61 months, respectively (P = .9).
Conclusions: These data suggest that MSI-H is not a common feature in resected CRC liver metastases and do not suggest a role for MSI in stratifying good versus poor prognosis in these patients.
Key Words: Microsatellite instability - Colorectal cancer - Hepatic metastases - Molecular markers
the Annual Meeting of the Society of Surgical Oncology, Los Angeles, California, March 5–9, 2003.