Effect Of Radiofrequency Ablation On Tumor Cell Apoptosis In Rabbit Tumor Model

Objective: Radiofrequency ablation (RFA), one of the ablation therapies, has been widely used to treat liver cancers, yielding excellent clinical results. Despite its efficacy, possible mechanisms that promote or interfere with the effects of radiofrequency ablation of liver tumors have not been clarified. The aim of this study was to observe the histopathological alterations in the periphery tissue around the RFA sites and the relationship between RFA and apoptosis in tumor.Methods: The VX2 tumor cells were planted in the hepatic left-central lobe of 32 rabbits. All animals were divided to two groups randomly, the RFA group (n=28) and the control group (n=4). The RFA group was treated with RFA after 24d, and were killed at 0, 2, 6, 12, 24, 48, 168h. The control group was intact. To assessed apoptosis of the treatment center and periphery tissue in RFA group and the tumor of control group, we examined morphological change through naked eye, microscope and transmission electron microscope, determined apoptosis index through the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method and DNA fragmentation through diphenylamine method.Results: The morphological change in treatment center of RFA group was coagulative necrosis. And in the periphery area of the coagulative necrosis zone we found apoptosis cells and necrosis cells through microscope and transmission electron microscope. The apoptosis index detected by TUNEL method and DNA fragmentation index detected by diphenylamine method were obviously higher than these of the control group and rose to peak value at 12h after operation (P<0.01) , then descended gradually.Conclusion: RFA treatment can induce the tumor cell apoptosis in the periphery area around the coagulative necrosis zone. Inducing the tumor cell apoptosis is a very important mechanism of RFA to treat malignant tumor.