Fate of metastatic foci after chemotherapy and usefulness of contrast‐enhanced intraoperative ultrasonography to detect minute hepatic lesions

Abstract

Along with advances in the chemotherapy for colorectal cancer, the strategy for hepatic metastasis has been changed. One of the most striking issues is that initially unresectable hepatic metastases can be resectable after chemotherapy with considerably high frequency. In addition, advanced chemotherapy leads to the downsizing of the metastatic foci in the liver, which is sometimes difficult to detect with conventional intraoperative ultrasonography (IOUS). To discover the undetectable hepatic lesions with IOUS, we have introduced contrast-enhanced intraoperative ultrasonography (CEIOUS). In the present study, we present evidence that viable cancer cells exist in even the shrunken tumors with high frequency and that CEIOUS contributes to detecting the minute foci. This study was composed of eight patients; four of them had initially unresectable metastasis, and the remaining four had either H2 or H3 status of hepatic metastases. All of them underwent hepatic resection after chemotherapy. A total of 57 metastatic lesions were detected before chemotherapy. Thirty lesions were demonstrated by CEIOUS with perflubutane and resected. In the pathological examination, tumor cells were not found in 12 of the 30 resected lesions. The degree of pathological liver damage was grade 1 or less in all patients, and no serious complication occurred after surgery in any of the patients. The present study showed that viable cancer cells remained with high frequency, even in the minute hepatic metastasis which was reduced in size after chemotherapy, and CEIOUS was a useful examination for detecting the minute hepatic foci.