Clinical Outcomes of Next-Generation Microwave Thermosphere Ablation for Hepatocellular Carcinoma with Primarily Hepatitis-Related Etiology

Background and aim: We investigated the clinical outcomes of patients with hepatocellular carcinoma (HCC) who underwent next-generation microwave thermosphere ablation (MTA). Methods: A total of 429 patients with 607 HCCs (maximum tumor diameter <= 40 mm) were included. We defined the following areas of the liver as those where MTA therapy is difficult to perform: caudate lobe and areas near the primary and secondary branches of the intrahepatic portal vein, inferior vena cava, gallbladder, heart, duodenum, abdominal esophagus, collateral veins around the liver, and spleen. Factors which predisposed patients to local tumor recurrence in the context of tumor location and complications were examined. Results: The primary etiologies of HCC were hepatitis-related: 259 (60.4%) cases of HCV, 31 (7.3%) cases of HBV, and two instances of both. Median maximum tumor diameter was 15.0 (interquartile range, 10.0-21.0) mm. There were 86 tumors in areas of the liver where MTA is difficult. The most common area was near the primary and secondary branches of the intrahepatic portal vein (26 nodules). The cumulative local tumor recurrence rates at 1, 2, and 3 years were 4.4%, 8.0%, and 8.5%, respectively. The cumulative local tumor recurrence rate differed significantly by tumor size group: 6.6%, 13.8%, and 29.4% at three years in the <= 20 mm group (n = 483), 20-30 mm group (n = 107), and >= 30 mm group (n = 17), respectively (p < 0.001). The cumulative local tumor recurrence rate was similar despite difficult-to-treat status (p = 0.169). In the multivariable analysis, tumor size (> 15 mm) (hazard ratio [HR], 2.15; 95% confidence interval [CI], 1.11-4.16; p = 0.023) and ablative margin (< 3 mm) (HR, 2.94; 95% CI, 1.52-5.71; p = 0.001) were significantly associated with local tumor recurrence. Only tumor size (> 15 mm) (odds ratio, 3.41 95% CI, 1.53-7.84; p = 0.026) was significantly associated with complications. Conclusions: MTA is a safe and effective local ablation therapy for HCC, even for tumors located in areas of the liver where local ablation therapy is difficult.