Percutaneous radiofrequency ablation of liver metastases in potential candidates for resection: the "test-of-time approach"

Background: Some surgeons have advocated delaying resection of liver metastases to allow additional metastases which may be present, but are undetected, to be identified. This "test-of-time" approach can limit the number of resections performed on patients who ultimately will develop additional metastases. The current study evaluated the potential role and possible advantages of performing radiofrequency (RF) ablation during the interval between diagnosis and hepatic metastasectomy as part of a test-of-time management approach.

Methods: Eighty-eight consecutive patients with 134 colorectal carcinoma liver metastases were potential candidates for hepatic metastasectomy. They were treated with percutaneous RF ablation using single (101 treatments) or triple-probe cluster (22 treatments) 18-gauge internally cooled electrodes. Treatment was performed under conscious sedation (22 of 119 treatments), anesthesia (14 of 119 treatments), or general anesthesia (83 of 119 treatments). At the time of the initial RF ablation procedure, 49 of 88 patients (56%) were found to have 1 metastasis, 32 of 88 patients (36%) had 2 metastases, and 7 of 88 patients (8%) had 3 metastases. Metastases ranged from 0.6 to 4.0 cm in greatest dimension (mean, 2.1 cm). Follow-up with serial computed tomography scans scans ranged from 18 to 75 months (median, 33 months) after the initial RF ablation.

Results: A total of 119 RF ablations were performed. Complete necrosis was obtained in 53 of 88 patients (60%) and in 85 of 134 lesions (63%). During follow-up of these 53 patients, 16 (30%) remained free of disease and 37 (70%) developed new lesions. New lesions were intrahepatic in 26 of 37 patients (70%), extrahepatic in 4 patients (11%), and both intrahepatic and extrahepatic in 7 patients (19%). Of 26 patients whose new lesions were intrahepatic only, 15 (58%) were retreated with RF and 7 were free of disease at the time of last follow-up (median follow-up, 28 months). Ten additional patients with only intrahepatic new lesions were deemed untreatable and 1 patient underwent resection. Overall, among the 53 patients in whom complete tumor necrosis was achieved after RF ablation therapy, 52 (98%) were spared surgical resection: 23 (44%) because they have remained free of disease and 29 (56%) because they developed disease progression. Among all 88 patients, 21 (24%) underwent resection after RF ablation (8 were free of disease at the time of last follow-up), 23 (26%) remained free of disease after successful RF ablation, and 56 (64%) developed untreatable disease progression (44 after RF alone, 12 after RF and surgery). Lesions in 35 of 88 patients (40%) demonstrated local tumor recurrence on follow-up imaging studies. Twenty of these 35 patients (57%) underwent surgical resection, whereas the remaining 15 patients (43%) developed additional, untreatable metastases. New lesions were intrahepatic in 9 of 15 patients (60%), extrahepatic in 1 of 15 patients (7%), and both intrahepatic and extrahepatic in 5 of 15 patients (33%). No patient who had been treated with RF ablation became unresectable due to the growth of metastases and there was no evidence of needle track seeding in any patient after RF ablation. Overall, among the 35 patients in whom complete tumor necrosis was not achieved after RF ablation therapy, 15 (43%) were spared surgical resection.

Conclusions: The results of the current study suggest that current RF ablation techniques, when used as part of a test-of-time management approach, can decrease the number of resections performed. The approach results in complete tumor necrosis in some patients and provide an interval for others who ultimately will develop new intrahepatic and/or extrahepatic metastases to do so.