Should microwave energy be preferred to radiofrequency energy for ablation of malignant liver tumors?

Background: Microwave ablation (MWA) and radiofrequency ablation (RFA) can destroy unresectable liver cancer, but the efficacy and safety of MWA are unclear. Objective: To compare survival between MWA and RFA performed during a similar time period. Methods: The study population comprised 51 patients undergoing open (88.2%) or laparoscopic (11.8%) MWA or RFA for hepatic malignancy during a 3-year period. Results: Twenty-one patients underwent MWA and 30 patients underwent RFA for 117 lesions, usually colorectal cancer. Most MWA (90%) and RFA (85%) patients underwent concurrent liver resection; 28.6% of MWA and 11.1% of RFA patients had previous liver surgery ( p =.15). The mean number of lesions ablated (2.6 vs 2.4), total ablation zone diameter (8.5 vs 7.2 cm), total ablation time (15 vs 17 minutes), and total surgical time (240.0 vs 228.8 minutes) were not significantly different for MWA versus RFA. With a median follow-up of 20.4 months, the median overall survival for MWA versus RFA patients was 18 versus 30 months (p =.50), or 32 versus 30 months for those with colorectal cancer (p =.57). Morbidity and mortality were not significantly different after MWA versus RFA. Conclusions: Although MWA and RFA appear to have equivalent survival and safety, MWA is easier to use.