Percutaneous radiofrequency ablation therapy of hepatocellular carcinoma using multitined expandable electrodes: Comparison of subcapsular and nonsubcapsular tumors

OBJECTIVE. Our objective was to compare the prognosis of subcapsular and nonsubcapsular hepatocellular carcinoma after percutaneous radiofrequency ablation using multitined expandable electrodes. MATERIALS AND METHODS. Some controversies exist about the clinical usefulness of percutaneous radiofrequency ablation of subcapsular hepatocellular carcinoma. Twenty-eight patients underwent percutaneous radiofrequency ablation of 43 hepatocellular carcinomas using multitined expandable electrodes. Twelve tumors were subcapsular and 31 were nonsubcapsular. We attempted to use normal liver as a pathway to the tumor when possible. Tumor size ranged from 1.0 to 4.2 cm (mean, 1.8 cm). Median follow-up was 16 months. Initial ablation was considered to have been complete when no enhancement was seen in the region of the ablated lesion on 1-month follow-up CT or on follow-up CT performed immediately after repeated ablation. Initial complete ablation and local tumor progression rates were compared between subcapsular and nonsubcapsular tumors. Eleven patients had subcapsular tumors (group 1), whereas the other 17 patients did not have subcapsular tumors (group 2). Major complication and mortality rates were compared between the two groups. RESULTS. No significant differences in initial complete ablation rate (100% vs 96.7%, p = 1.000) or local tumor progression rate (0% vs 10.0%, p = 0.545) were found between subcapsular and nonsubcapsular tumors. No procedure-related major complication or mortality occurred. The overall 1- and 3-year survival rates were 89.3% and 60.3%, respectively. CONCLUSION. The rates of local tumor progression and complications for radiofrequency ablation using multitined expandable electrodes for subcapsular hepatocellular carcinomas were comparable to those for nonsubcapsular hepatocellular carcinomas.