Radiofrequency ablation of hepatocellular carcinoma: Can subcapsular tumors be safely ablated?

OBJECTIVE. Our purpose was to retrospectively evaluate percutaneous radiofrequency ablation of unifocal subcapsular hepatocellular carcinoma (HCC) in comparison with nonsubcapsular tumors with regard to the technical and clinical outcomes. MATERIALS AND METHODS. A total of 42 patients (23 men and 18 women; age range, 22-83 years) with unifocal HCC underwent percutaneous radiofrequency ablation as their sole interventional treatment between May 1998 and August 2003. Subcapsular tumors were selected for ablation if there was no large exophytic component, and they were ablated through an indirect puncture, a gradual increase in radiofrequency power output, and needle track ablation. Technical effectiveness after single-session radiofrequency ablation, complications, local tumor progression, overall survival, and event-free survival rates were compared between the two groups. RESULTS. There were 15 patients with subcapsular HCC and 27 patients with nonsubcapsular HCC. The technical effectiveness was 93% (14/15) in the subcapsular HCC group and 96% (26/27) in the nonsubcapsular group (p > 0.99), complication rates were 0% (0/15) and 7.4% (2/27) (p = 0.53), and rates of local tumor progression were 21% (3/14) and 15% (4/26) (p = 0.68), respectively. No needle track or peritoneal seeding was found in either group. No significant differences were found in overall survival (3 years: 60% vs 56%; p = 0.78) and eventfree survival rates (3 years: 59% vs 48%; p > 0.99) between the two groups. CONCLUSION. Radiofrequency ablation of subcapsular HCC can be comparable to that of nonsubcapsular HCC with regard to the technical and clinical outcomes when there is proper patient selection and an optimized technique is used.