Evaluation of radiofrequency ablation as an alternative for the treatment of brain tumor in rabbits.

Radiofrequency ablation (RFA) has emerged recently as a promising therapy for extracranial malignancies. This experiment was conducted to explore the potential of RFA for the treatment of brain tumor in a rabbit model with imaging-histological assessment. Eighteen rabbits with intracranially implanted VX2 tumors of 0.9+/-0.2 cm in diameter were divided into two groups. Group A (n = 12) was treated with a cooled-tip RFA technique at 30 watts for 30-60 s. Group B (n = 6) received sham operation. The therapeutic efficacy was evaluated by comparing survival rate, magnetic resonance imaging (MRI) and histological findings. All animals in Group B died within one month after tumor implantation (19+/-2.6 days). Tumor eradication was achieved in 6/12 rabbits (50.0%) in Group A, of which three rabbits survived longer than three months, another three rabbits were found free of viable tumor when sacrificed. Five rabbits suffered from local tumor relapse. One rabbit developed intracranial metastasis to the brain stem despite a complete ablation of the original tumor. Three-month survival rate of RFA treated rabbits was significantly higher (p < 0.05) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of three characteristic concentric zones, which corresponded to central coagulative tissues (Zone A), peripheral hemorrhagic rim (Zone B) and interstitial edema (Zone C) on histology. This study suggests that RFA may become a promising alternative therapy for the treatment of brain tumor. The recognized characters of thermal lesion on MRI and histology may prove valuable in delimitating the ablation range and understanding the biological response of the RFA.