| PART I CT-guided radiofrequency ablation of rabbit VX2lung tumorsPurpose:In this study, we investigated CT-guided radiofrequency ablation (RFA) of rabbit VX2lung tumors, with the aim to observe CT images and pathologic regression, to evaluate efficacy and explore treatment parameters of RFA. Materials and Methods:Build the model of rabbit VX2lung tumors with a new method of CT-guided coaxial trocar percutaneous puncture. The experimental group included27rabbits with RFA, and the control group consisted of9rabbits without treatment. Two groups were performed CT scans at different time points to observe CT images. For the experimental group,18were killed at different time points to observe pathologic regression; while the rest was kept natural death, evaluating efficacy and calculating the survival time. The control group had natural death and the survival time was calculated. Results:CT images taken immediately after RFA showed the lung tumor surrounded by ground-glass opacity (GGO), sometimes, with a cavity or small vacuoles in the lesion. It couldn’t exclude the residual of tumor cells even without enhancement in CT scans according to pathological findings of the tissue samples. Twenty-four hours after operation, in gross anatomy, the area of RFA showed four zones from inside to outside along power gradient:the carbonization or evaporation center, gray coagulation necrosis zone, red-brown hemorrhage zone and pink hyperemic exudate zone. There was some degree of inflammation pathologically around the lesion after operation, which was absorbed within four weeks mainly; eventually, left thick-walled fibrous tissue encysting coagulation necrosis and slightly remote hemorrhage. The rate of complete response of the experimental group was78%. The survival time of the experimental group and the control group had significant difference (t=2.634, P=0.018), which was38±5.9d and24±3.1d, respectively. The linear regression equation between RF energy and the maximal lesion size was y=-2.3372+1.4361x, with test of regression coefficient P=.000. Conclusion:The method of CT-guided coaxial trocar percutaneous puncture to build the model of rabbit VX2lung tumors was safe and rapid, with high tumor formation rate. Our study showed not only safety, micro-invasion and low rate of complications but also definite efficacy of RFA for lung tumors. To evaluate efficacy, one month after operation could be the new baseline due to the development and succession of the RFA area. There was relationship of linear regression between RF energy and the maximal lesion size. PARTⅡ CT-guided radiofrequency ablation of lung malignant tumors: the preliminary results of a prospective, single center clinical trialPurpose:The purpose of this study was to investigate the safety, feasibility, and effectiveness of radiofrequency ablation of lung malignant tumors, to explore the relative factors influencing complete ablation and evaluation criteria of response postablation. Materials andMethods:Between January,2012and March,2013, a series of24patients with47lung lesions were performed35sessions of radiofrequency ablation. All the patients were considered to be unsuitable for surgery, radiotherapy or chemotherapy by multidisciplinary team. The pathologic diagnoses of the47lung lesions were obtained via biopsy. The patients were followed for3to13months (mean6.3±3.1). Primary endpoints of the present study were safety, technical success, and local effectiveness. Second endpoints were time to local progression (TTLP) and progression-free survival (PFS). The data of images of preablation and postablation and local effectiveness were collected to analyze the relative factors influencing complete ablation and identify evaluation criteria of response postablation. Results:No perioperative death occurred in any of the35sessions of radiofrequency ablation. Major complications were as follows:pneumothorax11.4%(4/35), one needed chest tube drainage; stubborn pneumothorax and hemothorax2.9%(1/35), which needed negative pressure drainage; pleural effusion5.7%(2/35), one needed chest tube drainage. Technical success rate was97.9%(46/47), small lesion size and occurrence of pneumothorax resulted in one technical failure. According to revised response evaluation criteria in solid tumors (RECIST), complete response rate of target lesions was93.6%(44/47) lasting at least3-month postablation. By the last follow-up, the time to local progression and progression-free survival was6.0±2.9months and5.1±2.8months, respectively. Lesion size and position relation between the lesion and large vessels were two influential factors of complete ablation. Lesion size larger than3cm and lesions adjacent to large vessels had lower complete ablation rate, the difference was statistically significant (P=0.001、P=0.001). There was no significant difference of complete ablation rate when ground-glass opacity immediately after ablation was between5and10mm and larger than10mm (P=0.910). Compared with original size, we found the lesion size increased first after ablation; and then got smaller even disappeared. The lesion size at1-month postablation was larger than original size, while smaller than that of3-month postablation, the difference was statistically significant (P=0.000、P=0.000). Conclusion:Radiofrequency ablation yields high safety, feasibility and local control of lung malignant tumors. Lesion size larger than3cm and lesion position adjacent to large vessels are factors against complete ablation. It is of great clinical value to evaluate local efficacy by revised RECIST criteria, taking1-month postablation as a new baseline and evaluating local effectiveness at least3-month after ablation. |
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