2:50 PM Abstract No. 91 - Factors affecting oncologic outcome after radiofrequency ablation of colorectal liver metastasis

Abstract

Purpose To assess factors affecting oncologic outcomes of percutaneous radiofrequency ablation (RFA) in the management of colorectal liver metastases. Materials and Methods One-hundred-forty-nine patients (86 men and 63 women, median age: 61 years) underwent a total of 198 RF ablation sessions for the treatment of 218 lesions from January 2003 to March 2012. Technique effectiveness per lesion was evaluated at the 4-6-week post ablation CT and local tumor progression (LTP) at the ablation site was assessed reviewing subsequent scans. The endpoints of the study were: LTP-free survival and overall survival (OS) from the time of the ablation. Clinical factors such as: tumor size, prior hepatic resection, node positivity of the primary, time interval from primary resection to liver metastasis, number of tumors, presence of extrahepatic disease, pre and post ablation systemic and intraarterial chemotherapy were analyzed for their effect on outcomes. LTP-free survival and OS were calculated using Kaplan-Meier methodology. Factors affecting oncologic outcome were assessed in univariate and multivariate analysis. Results Median tumor size was 1.9 cm (range 0.5 to 5.7 cm). Complete ablation was demonstrated in 209 cases (technique effectiveness rate: 96%). Median overall survival was 35.43 months. One-, 3-, and 5-year overall survival rates were: 91%, 47% and 33%, respectively. On univariate analysis, as well as multivariate analysis tumor size over 3 cm (HR: 2.58, 95% CI: 1.47, 4.53; p=0.001) and not receiving systemic chemotherapy following RFA (HR: 0.63, 95% CI: 0.4, 0.98; p=0.04) were independent predictors for shorter OS. Median LTP-free survival was 25 months. Size (p=0.01), prior systemic (p=0.02) and prior intraarterial chemotherapy (p=0.03) were independent factors for LTP-free survival in the univariate model, however only size retained its significance in the multivariate model (p=0.01). Conclusion Size of ablated tumor and post-ablation chemotherapy are associated with better oncologic outcomes after RFA of colorectal liver metastases.