Liver Resection for Metastatic Colorectal Cancer: Assessing the Risk of Occult Irresectable Disease

BACKGROUND: Liver resection is standard therapy for selected patients with metastatic colorectal cancer. Extrahepatic metastases and inability to remove all hepatic disease usually preclude curative resection and are the most common contraindications. This study analyzes irresectability in patients considered to have resectable disease taken to operation for potentially curative hepatic resection. We describe preoperative factors associated with irresectability and propose a preoperative scoring system that identifies patients at particularly high risk for occult irresectable disease. STUDY DESIGN: Patients considered to have resectable hepatic colorectal metastases were identified from a prospective database. Intraoperative findings that precluded liver resection were recorded. Demographic data, characteristics of the primary tumor, and characteristics of the hepatic metastases were recorded and analyzed. RESULTS: From April 1992 through July 1997, 416 patients were explored with the intention of performing a potentially curative liver resection; 329 (79%) were resected. Eighty-seven patients (21%) had apparently resectable tumors on preoperative imaging but irresectable disease at laparotomy. Forty-four patients (51%) had irresectable disease limited to the liver; 32 had extensive bilobar disease not appreciated before surgery, and 12 were not resected for technical or other reasons unrelated to disease extent. Forty-three patients (49%) had extrahepatic disease, 31 of whom had resectable hepatic tumors. Of the several preoperative factors analyzed, only the estimated number of hepatic tumors was an independent predictor of irresectable findings at operation. This held true for patients with extrahepatic metastases and those with extensive hepatic disease. From these data, we devised a preoperative scoring system that estimates the probability of finding occult irresectable disease. Resectability ranged from 95% in patients with a score of 0 (solitary, unilobar) to 62% in those with a score of 3 (multiple, bilobar; p = 0.0001). The predictive value of this scoring system was then validated by applying it prospectively to an additional group of 118 patients taken to surgery for resection; the results were similar. CONCLUSIONS: Standard preoperative investigations predicted resectability in 79% of patients with hepatic colorectal metastases. Unresectable disease limited to the liver and extrahepatic disease were seen with nearly equal frequency. The majority of patients with extrahepatic metastases had resectable hepatic disease (31 of 43, 72%). A preoperative scoring system is proposed that identifies patients at high risk for unrecognized irresectable disease and may help focus the use of additional diagnostic modalities such as laparoscopy and positron emission tomography (PET).