Radiofrequency Ablation for the Treatment of Hepatocellular Carcinoma Just Below the Hepatic Capsule

Background/Objectives: During radiofrequency ablation (RFA) for the treatment of hepatocellular carcinoma (HCC), electrodes are generally inserted into the center of the tumor through the hepatic parenchyma under image guidance, including ultrasound or computed tomography (CT) guidance. However, tumors located just below the hepatic capsule require special puncture techniques. This retrospective study aimed to analyze the efficacy and outcomes of RFA for HCC located just below the subcapsular region of the liver. Methods: A total of 81 patients with 81 subcapsular HCC tumors underwent RFA. Baseline patient characteristics, treatment results, and adverse events were investigated. Factors associated with local recurrence were also examined. Results: Among the 81 patients, 59 (73%) were male, the median age was 74 years (range, 46–93 years), and 68 (84%) were classified as Child-Pugh class A. The median tumor size was 1.5 cm (range, 0.5–3.7 cm), and 56 of 81 tumors (69%) were <2.0 cm in diameter. 53 tumors were located in the right lobe of the liver (65%). Monopolar RFA was performed in 55 patients (68%), and no-touch multi-bipolar RFA was performed in 26 patients (32%). Treatment success was achieved in 75 tumors (93%), with inadequate ablative margins observed in 6 tumors (7%). Of these six tumors, five (83%) were treated with monopolar RFA; however, differences between the RFA devices were not statistically significant (p = 0.368). Local tumor progression (LTP) was observed in 19 patients (24%), with cumulative LTP rates of 13%, 29%, 33%, and 33% at 1, 3, 5, and 10 years, respectively. Multivariate analysis using a COX proportional hazards model identified insufficient ablative margins as a significant factor associated with LTP (hazard ratio, 4.64; 95% confidence interval, 1.14–14.9; p = 0.031). Adverse events occurred in 17 patients (21%), all of whom recovered with conservative treatment. Tumor seeding occurred in only one patient (1%). Conclusions: In the present study, achieving an adequate ablative margin using either monopolar or multi-bipolar RFA systems was associated with a reduced risk of local tumor recurrence in patients with subcapsular HCC.