Existence of microscopic residual viable lesions in patients with colorectal liver metastases after chemotherapy.

BACKGROUND/AIMS: Hepatic metastases from the colorectal carcinoma frequently recur after resection and microscopic residual cancer lesions (RCL) could be important in the development of recurrence. The aim of our study was to investigate an existence of microscopic RCL after modern chemotherapy and its correlation with the preoperative CT imaging. METHODOLOGY: Thirteen patients who underwent liver resection for colorectal liver metastases (CRM) after preoperative chemotherapy were studied. Resected hepatic specimens were stained with an antibody against carcinoembryonic antigen to detect microscopic RCL, which were defined as discrete microscopic cancerous lesions surrounding the dominant metastases. Also, we evaluated the correlation between the outline of CRM based on CT finding and the detection of microscopic RCLs around CRM. RESULTS: RCL were found immunohistochemically in 10 patients (77.8%). There are one patient whose RCL was most distant from the main tumor more than 10 mm. The presence of microscopic RCL was associated with the irregular outline of CRM (2/13, 15.4%) compared with regular CRM (11/13, 84.6%). CONCLUSIONS: To plan hepatectomy for CRM after chemotherapy, the possible existence of microscopic RCL should be taken into account. In addition, irregular shape tumor on CT should have wider surgical margin than 10 mm.