Microwave Ablation for the Treatment of Malignant Liver Tumors Closed to Intrahepatic Vessels

Liver cancer including primary hepatocellular carcinoma (HCC) and metastatic liver cancers is one the most common malignancies in the world. Over 10000 new cases per year are diagnosed in Taiwan. Despite the many treatment options, the prognosis of HCC remains dismal. More than 8000 people died of this cancer every year in Taiwan. A majority (70% to 85%) of patients present with advanced or unresectable disease. In contrast, small liver cancers can be cured with an appreciable frequency. Five-year disease-free survival exceeding 50% has been reported for surgical resection, and for the inoperable patients who do not have vascular invasion or extrahepatic spread. Radiofrequency ablation (RFA) is recommended as an alternative curative therapy. However, the main drawback of RFA is its limitation to tumor size and location. The tumors larger than 5 cm in diameter or located adjacent to vessels, could not be ablated completely sometimes. Microwave ablation (MWA) can ablate tumor by higher temperature than RFA, so is supposed not to be diminished by adjacent vessels.