Microwave tumor ablation: Cooperative academic-industry development of a high-power gas-cooled system with early clinical results

Microwave tumor ablation continues to evolve into a viable treatment option for many cancers. Current systems are poised to supplant radiofrequency ablation as the dominant percutaneous thermal therapy. Here is provided an overview of technical details and early clinical results with a high-powered, gas-cooled microwave ablation system. The system was developed with academic-industry collaboration using federal and private funding. The generator comprises three synchronous channels that each produce up to 140W at 2.45GHz. A mountable power distribution module facilitates CT imaging guidance and monitoring and reduces clutter in the sterile field. Cryogenic carbon-dioxide cools the coaxial applicator, permitting a thin applicator profile (similar to 1.5 mm diameter) and high power delivery. A total of 106 liver tumors were treated (96 malignant, 10 benign) from December 2010 to June 2012 at a single academic institution. Mean tumor size +/- standard deviation was 2.5 +/- 1.3cm (range 0.5-13.9cm). Treatment time was 5.4 +/- 3.3min (range 1-20min). Median follow-up was 6 months (range 1-16 months). Technical success was reported in 100% of cases. Local tumor progression was noted in 4/96 (4.3%) of malignancies. The only major complication was a pleural effusion that was treated with thoracentesis. Microwave ablation with this system is an effective treatment for liver cancer. Compared to previous data from the same institution, these results suggest an increased efficacy and equivalent safety to RF ablation. Additional data from the lung and kidney support this conclusion.