Abstract: Objective To investigate the efficacy of high-powered microwave ablation （MWA） in treating patients with small and large hepatocellular carcinoma （HCC） and to clarify the safety and the risk factors of recurrence after percutaneous MWA. Methods A total of 45 patients with hepatitis B virus （HBV） associated HCC,who had not received any treatment before percutaneous MWA,were enrolled in this study. All patients received MWA by using high power[（80-100 W） and （2450±10 ） MHz] through percutaneous approach. The procedure was carried out for a total of 60 lesions with the diameter of 3 to 8 cm. The patients were divided into two groups,e.g. 46 in small tumor group （3-5 cm） and 14 in big tumor group （5-8 cm）. The local tumor ablation rates between the two groups were compared. The recurrence, complications and the therapeutic efficacy were recorded. The contrast enhanced ultrasound and the contrast enhanced CT or MRI was performed one month after microwave ablation.The factors related to HCC recurrence were analyzed by using univariate analysis and multivariate analysis. Result The complete ablation rates for the first ablation in the small tumor group was significantly higher than in the big tumor group （82.6% vs. 64.3%,P=0.037）,and the complete ablation rates for the second ablation were 100.0% in the small tumor group and 85.7% in the big tumor group（P>0.05）;After the MWA,no skin burn or death occurred;Ten（22.2%） of 45 patients developed recurrence after ablation and the one-year and two-year survival rates were 95.6% （43/45） and 86.7（39/45）;Univariate analysis showed that a positive correlation existed between the lesion’s number,proximity to a major bile duct,pre-ablation serum α-fetoprotein（AFP） levels,serum HBV DNA positive and early recurrence and multivariate analysis identified HBV DNA（P=0.031） and proximity to a major bile duct（P=0.039） as the independent prognosis factors causing postoperative HCC recurrence. Conclusion The complete ablation rate of high-powered percutaneous MWA in the small tumor group is higher than in the big tumor group and high-powered percutaneous MWA appears to be a safe and effective treatment with fewer complications for patients with HCC. HBV DNA and proximity to risk area are the independent prognosis factors causing postoperative HCC recurrence.

Key words: Hepatocellular carcinoma, Microwave ablation, High-powered, Recurrence, Risk factor