Microwave Coagulation/Ablation in Combination with Sorafenib Suppresses the Overgrowth of Residual Tumor in VX2 Liver Tumor Model

Objectives: Our study is to evaluate the effect of thermal ablation on residual VX2 tumor tissue and the efficiency of sorafenib as an adjuvant therapy after insufficient microwave coagulation (MWC) on a rabbit VX2 liver tumor model. Methods: Thirty-seven rabbits with orthotic VX2 liver tumors were randomly divided into MWC group (n=11), combination treatment group (n=14), and control group (n=12). The therapeutic efficacy was evaluated by contrast enhanced ultrasound (CEUS), magnetic resonance imaging (MRI), pathological and immunohistochemical examinations. Analysis of enhancement characteristics included enhancement level, pattern, and location. The necrotic degree of tumor was analyzed by semi-quantitative classification. The apparent diffusion coefficiency (ADC) was calculated using diffused weighted image (DWI). Results: The tumor growth was accelerated in MWC group compared with control group and combination treatment group. A low metastasis rate was shown in combination treatment group compared with other two groups. The degree of necrosis in combination treatment group was greater than that in MWC group. The ADC value on DWI was higher compared with that of the control and MWC group, with statistical significance (P<0.05). With adjuvant therapy of sorafenib after insufficient ablation, the microvessel density (MVD) was lower than that of control group, whereas in MWC group the MVD was higher than that of control group, with statistical significance (P<0.05). Conclusion: Insufficient thermal ablation promotes residual tumor progression. While the adjuvant therapy of sorafenib serves as an effective way to suppress the overgrowth and neovascularization of residual tumor after insufficient thermal ablation.