Background. Hepatic resection for colorectal metastases has been established as the best option for patients with 4 or less lesions meeting specified criteria. Recently, the use of intraoperative ultrasound has increased the detection of previously occult liver lesions, and cryotherapy has allowed the treatment of liver lesions in inaccessible areas with less destruction of normal liver in the case of multiple lesions. We prospectively performed hepatic resection or cryotherapy to test the hypothesis that more than 4 liver metastases could be safely and successfully treated with improved long-term survival. Methods. From August 1993 to January 1999, 137 patients with liver metastases from colorectal cancer were treated with hepatic resection or cryotherapy at the Medical College of Wisconsin. Preoperative and postoperative computed tomography scans, intraoperative assessments of lesion number and curability, number of blood transfusions administered, length of stay, complications experienced, and overall survival rates were reviewed. Results. One hundred thirty-seven patients were explored. Treatment consisted of resection alone in 34, cryotherapy alone in 20, both treatments in 52, and no treatment was possible in 31 patients. 'Curability' was defined as complete resection or cryotherapy of all identifiable tumor at the conclusion of the operation. A Cox proportional hazards model demonstrated that survival was determined by the destruction of all identifiable metastases (P < .001) and was not statistically influenced by age, gender, type of therapy, or the number of metastases treated. Conclusions. Surgical treatment of colorectal liver metastases remains the best option for patients with this disease. A key factor in overall survival is the destruction or resection of all identifiable disease and not the number of tumors per se. Using cryotherapy as an addition to the surgical arsenal, patients previously deemed unresectable because of the number of lesions have a chance for long-term survival. This study demonstrates improved long-term survival for 'cured' patients with more than 4 metastatic lesions, thereby extending the indications for resection/ablation.
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