The purpose of this study is to compare microwave ablation using the Acculis Microwave Tissue Ablation (MTA) System with conventional radiofrequency ablation (RFA) using Covidien cool-tip radiofrequency needle in patients with localized unresectabe hepatocelluar carcinoma (HCC).

The investigators hypothesize that microwave ablation can achieve a better complete ablation rate as compared to radiofrerquency ablation.

A randomized comparative study is performed by randomly assigned participants to microwave ablation arm or radiofrequency ablation arm. The efficacy of treatment outcome is assessed by the complete tumor ablation rate at 1 month, recurrence rate and survival time of participants. Safety of the procedures is also compared between the 2 treatment arms.

Inclusion Criteria:

• Age >18 years
• Unresectable hepatocellular carcinoma (HCC) and tumor amendable for local ablation
• Resectable HCC but patient opts for local ablation
• Maximum diameter of tumor ≤6cm
• Maximum number of tumor nodules ≤3
• Absence of radiology evidence of major vascular or bile duct invasion
• Child's A or B liver function
• Karnofsky performance status ≥70%

Exclusion Criteria:

• Informed consent not available
• Pregnant female patients
• Tumors unfavourable for local ablation (e.g. tumor close to porta hepatis)
• HCC with history of rupture
• Concomitant hepatectomy
• Patients with chronic renal failure