Radiofrequency ablation for eradication of renal tumor in a rabbit model by using a cooled-tip electrode technique

Background: Radiofrequency ablation (RFA) has emerged as a potential alternative for surgery in clinical oncology. This animal experiment was conducted to evaluate the feasibility of RFA in the treatment of renal tumor. Methods: Eighteen rabbits with renal implantation of VX2 tumors were divided into two groups. Group A (n = 12) was treated with RFA by using a cooled-tip RF system at 30 W for 80 to 180 seconds. Group B (n = 6) received a sham operation. The therapeutic efficacy was evaluated by survival rate, magnetic resonance imaging (MRI), and histology. Results: All animals in group B died within 3 months after tumor implantation. Total tumor eradication was achieved in 10 of 12 rabbits (83.3%) in group A, of which 5 rabbits survived longer than 6 months (absolute eradication) and another 5 rabbits were found free of viable tumor when killed (relative eradication). Two rabbits experienced local tumor relapse, lung metastasis, or both. Six-month survival rate of RFA-treated rabbits was significantly higher (P < .01) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of five characteristic concentric zones, which corresponded to central needle track (zone A), tumor coagulation (zone B), renal tissue coagulation (zone C), peripheral hemorrhage (zone D), and inflammatory layer (zone E) on histology. Conclusions: RFA may become a promising therapy for the treatment of renal tumor. MRI is a useful modality for assessment of renal tumor ablation.