Experimental Study And Clinical Efficacy On Radiofrequency Thermal Ablation Of Hepatocellular Carcinoma

Objective To study the optimal technique, histopathologic characteristics of radiofrequency liver ablation and evaluate the therapeutic safety, efficacy of radiofrequency ablation on hepatocellular carcinoma. Methods The RF2000 radiofrequecy generator and the LeVeen electrode were used in 5 pig models and 78 HCC patients. In animal experiments,five pigs underwent radiofrequency liver ablation at varying power settings including 30W,50W,70W,90W,single-phase ablation(initial power at 50W and then lOW increments every minute to 90W) and two-phase ablation(after phase 1 completion, wait 30 seconds, restart in place at 70 power).Local tempretures were monitored during RFA and all lesions were inimediately examined both grossly and histologically after RFA. The extent of necrosis was assessed by H&E staining and NADH-diaphorase staining and electron microscope. In the noncontroled clinical study, 78 HCC patients were treated percutaneously under ultrasound guidance and followed up at regular intervals to assess efficacy, treatment-related complications, treatment response and local recurrence of the ablated tumors. Results The larger lesions were produced by power SOW, single-phase ablation or two-phase ablation, compared with the smaller lesions when the power was applied at 70W or 90W. Among these , the two-phase ablation was the most optimal approach with 4cm lesion in diameter. All lesions consistently resulted in a region of central coagulation which demonstrated no viable cells by NADH staining and a 2mm.4.hemorrhagic rim showing cell viability partly. Except 30W guoup, the tissue temperature elevated beyond 800C. In 78 patients, 105 times RFAs were used to treat 110 tumors. The patients were followed up mean 9.2 months, 43(55.1%) patients were alive with or without disease, among whom 31 patients(39.7%) were free of tumor. 6 patients(7.7%) had complications, but no treatment-related death or hepatic failure took place. The serum liver function tests(ALT,BIL)that were transiently elevated after RFA ,but returned to baseline values in all patients by 2 weeks.The common response after RFA was mild fever. Local tumor recurrence at the RFA site developed in 23 patients (29.5%). There were not significant difference in sex, age, cirrhosis, Child class, tumor differentiation, combined therapy, portal vein embolism or overlapping ablation sessions between the group that local tumor recurred and the group that did not (P>0.05),but the tumor diameter in the group that recurred was significantly larger than the group that did not recurred(8.38 ± 2.61cm versus 5.23 ±2.56cm, P0.0001),indicating that tumor local recurrence was closely related to the tumor diameter. Conclusion The two-phase application of AX energy is an optimal technique producing a sphere-like coagulated necrosis in 4.0cm diameter. Percutaneous RFA of HCC appears to be a safe, well-tolerated, minimally invasive, effective thermal ablation therapy. With overlapping ablation technique, current RFA devices might reliably ablate tumors smaller than 6cm in diameter, acting as surgical resection. Because of the relatively high rate of recurrence at intrahepatic sites other than RFA sites, consideration should be taken to combine other therapy such as hepatic-directed or systemic chemotherapy and immunotherapy in HCC patients.