Clinical results of radiofrequency hyperthermia for malignant liver tumors

To evaluate thermometry and the clinical results of radiofrequency (RF) hyperthermia for advanced malignant liver tumors.

One hundred seventy-three patients with malignant liver tumors treated between 1983 and 1995 underwent hyperthermia. The 173 tumors consisted of 114 hepatocellular carcinomas (HCCs) and 59 non-HCCs (47 metastatic liver tumors and 12 cholangiocarcinomas). Eight-megahertz RF capacitive heating equipment was used for the hyperthermia. Two opposing 25-cm electrodes were generally used for heating the liver tumors. Our standard protocol was to administer hyperthermia 40-50 min twice a week for a total of eight sessions. The liver tumor temperature was measured by microthermocouples when possible. Transcatheter arterial embolization, radiotherapy, immunotherapy, and chemotherapy were combined with hyperthermia treatment in accordance with each patient's liver function.

One hundred forty (81%) of the 173 patients who underwent more than four sessions of hyperthermia were evaluated in this study. Thermometry was performed in 77 (55%) of these 140 patients. The maximum tumor temperature, average tumor temperature, and minimum tumor temperature in the HCC were (mean +/- standard error) 41.2 +/- 0.2 degrees C, 40.3 +/- 1.3 degrees C, and 40.1 +/- 0.2 degrees C, respectively. The same thermometry results for non-HCC were 42.3 +/- 0.2 degrees C, 41.2 +/- 0.2 degrees C, and 40.9 +/- 0.2 degrees C, respectively. The maximum and minimum temperatures (41.8 +/- 0.2 degrees C and 40.3 +/- 0.4 degrees C) in the patients with a complete or partial response (CR or PR) were higher than those in the patients with no response or progressive disease (NR or PD) (41.3 +/- 0.5 degrees C and 39.8 +/- 0.4 degrees C), but the difference was not significant. Of the 73 cases with HCC who were evaluated by computed tomography (CT), CR was achieved in 7 (10%), PR in 15 (21%), NR in 37 (51%), and PD in 14 (19%). Of the 45 cases involving liver metastases evaluated by CT, CR was achieved in 3 (7%), PR in 17 (38%), NR in 12 (27%), and PD in 13 (29%). The 1-year cumulative survival rate for HCC patients was 30.0%, and the 5-year survival rate was 17.5%. The 1-year survival of non-HCC patients was 32.5%, and the longest survival was 30 months. The sequelae of hyperthermia included focal fat necrosis in 20 patients (12%), gastric ulceration in 4 (2%), and liver necrosis in 1 (1%). The sequelae of thermometry were severe peritoneal pain in seven patients (11%), intraperitoneal hematoma in one (1%), and pneumothorax in one (1%).

Even though the thermometry results for liver tumors were not satisfactory, the treatment results are promising. Further clinical trials of RF capacitive hyperthermia for the treatment of advanced liver tumors should be encouraged.