MICROMETASTATIC COLORECTAL-CANCER LESIONS IN THE LIVER

A surgical resection of metastatic liver lesions from colorectal cance r contributes to an improved prognosis. However, the postoperative rec urrence rate remains high, particularly in the residual liver. This is probably the result of the failure to detect small lesions. In the pr esent study, we histologically examined the presence of intrahepatic m icrometastases, which are considered to be related to recurrence in th e residual liver. Intrahepatic micrometastases were histologically exa mined in 31 resected specimens of 25 patients undergoing a hepatic res ection because of metastasis to the liver from colorectal cancer. Micr ometastases were found in 14 of 25 cases (56.0%), They were located in the portal veins, central veins, sinusoid, and bile ducts. The longes t distance from the main metastasis was 38.2 (mean 7.5 +/- 8.0) mm. Th e size of the macrometastases became larger, and the frequency of micr ometastases and the distance Df micrometastases from macrometastases h ad a tendency to increase. Continuous invasion of the macrometastases into the micrometastases through the vasculature or bile duct was also observed, These results suggested that some micrometastases observed in the metastatic liver from colorectal cancer were thus seeded from t he primary lesions, while other micrometastases originated from the ma crometastatic lesions as satellite lesions.