Impact of ablation algorithm versus tumor-dependent parameters on local control after microwave ablation of malignant liver tumors.

BACKGROUND The aim of this study is to assess the effect of tumor versus ablation-algorithm dependent parameters on local recurrence (LR) after microwave ablation (MWA) of liver malignancies. METHODS This was an institutional review board-approved study of patients who underwent laparoscopic or open MWA of malignant liver tumors. The impact of ablation algorithm (stepwise or direct heating, single or overlapping ablations, and ablation margin) and tumor-dependent (type, size, location, and blood vessel proximity) parameters on LR was analyzed using Kaplan-Meier and Cox proportional hazards. RESULTS A total of 179 patients with 602 liver tumors underwent 200 MWA procedures. Colorectal liver metastasis (CLM) was the most frequent tumor type followed by neuroendocrine liver metastasis (NELM), other metastatic tumors, and hepatocellular cancer (HCC). For patients followed at least a year with imaging, LR rate was 8.8% per lesion and 13.1%,1.3%, 11.7%, and 12.6%, for CLM, NELM, HCC, and other tumor types, respectively. On multivariate analysis, independent predictors of LR included tumor type, tumor size, and ablation margin. CONCLUSION LR after MWA for malignant liver tumors is predicted by both tumor and surgeon-dependent factors. Variations in the ablation algorithm did not affect LR, leaving the ablation margin as the only parameter that could be modified to optimize local tumor control.