Presence of microsatellite lesions with colorectal liver metastases correlate with intrahepatic recurrence after surgical resection.

Hepatectomy is the treatment of choice for patients with resectable colorectal carcinoma metastases. However, recurrences occur in about half to two-thirds of the patients after surgery. To reduce the recurrence rate, it is important to isolate those factors that influence intrahepatic recurrence. In this study, we assessed histopathological factors associated with intrahepatic recurrences in 53 cases of liver metastases with special reference to microsatellite metastases. In 18 of the 53 cases, the entire resected liver tissue block was sectioned, processed into H&E slides, and examined microscopically. For the 53 cases, 1-, 3-, and 5-year survival rates were 87.9, 65.7 and 46.1%, respectively, with a median survival of 74 months. Univariate analysis showed a significant association of intrahepatic recurrence (p=0.039), intra- or extrahepatic recurrence (p=0.003), and surgical margin status of <1 mm (p=0.013) with poor overall survival. Multivariate analysis showed that intra- or extrahepatic recurrence was an independent indicator of poor overall survival (p=0.034). In the fully examined 18 cases, intrahepatic recurrences were significantly associated with microsatellite metastases around the main metastatic tumors. Microsatellite metastases were detected in 10 cases (55.5%) and showed a trend toward a worse overall survival. Moreover, all microsatellite lesions were found within 4 mm from the advancing margin of the main metastases, and most of them (7/10) were located within 2 mm of the tumor border. Collectively, a surgical margin of 1 mm at least is needed, however, a minimum surgical margin of 2 mm seems preferable based on the distribution of intrahepatic recurrence-associated microsatellite lesions.