An Experimental Study On Radiofrequency Ablation Combined With Hepatic Arterial Embolization In A Rabbit Hepatocellular Carcinoma Model

Objectives: To study the biological behavior of remnant tumor of hepatocellular carcinoma (HCC) after radiofrequency ablation (RFA) combined with transcatheter arterial embolization (TAE); to investigate the mechanism of the combined therapy; and to assess the therapeutic efficacy of it.Methods: Forty-five New Zealand white rabbits were implanted percutaneously with VX2 tumor cells in the left lobe of the liver under CT guidance successfully. Three weeks later, there was a focal tumor (φ2.5cm-2.7cm) in the liver of each rabbit. Then they were divided into 3 groups at random: control group (pseudo-therapy group), RFA (single electrode 2.0cm exposure) alone group and 7 days after TAE combined with RFA (single electrode 2.0cm exposure) sequentially group. Each group was divided into 3 subgroups respectively according to the killing time: 1 day, 4 days and 7 days after treatment. All the 45 rabbit-models were sacrificed after treatment and their tissues,including peripherial tumor and central tissue of the ablation area,were sectioned, embedded in paraffin, fixed in 10% Formalinand and spitted constantly with 4μm–section. They were examined pathologically by HE dying and immunohistochemical methods (Apoptosis, CD31, VEGF, PCNA). The results of immunohistochemistry were compared. All the data were analysed by SPSS 13.0 software. Quantitative data were showed by x±s, P<0.05 was defined as threshold for statistical significance .Results: 1. Quantification assay of apoptosis measured by TUNEL and Caspase-3 staining methods indicated that apoptosis index (AI) in the margin of the tumor after RFA alone and combined therapy were both higher than that of control group significantly (P<0.01), they reached their peaks at 1 day, and decreased gradually along with the time to a low level at 7 days after treatment , but were still higher than that of pre-treatment . And AI of each subgroup after combined therapy were higher than that of RFA alone therapy significantly (P<0.01) . 2. Proliferation index (PI) of survival tumor cells after RFA alone and combined therapy were both lower than control group significantly (P<0.01) , and PI of each subgroup after combined therapy were lower than that of RFA alone therapy (P<0.05) . 3. Vascular endothelial grow factors (VEGF) of survival tumor cells after RFA alone and combined therapy were both lower than control group significantly (P<0.05). VEGF of each subgroup after combined therapy were higher than VEGF of RFA alone therapy slightly , but there was no statistical significance between them (P<0.05). 4. Microvessel density (MVD) of survival tumor cells after RFA alone and combined therapy were both lower than control group significantly (P<0.01) . MVD of each subgroup after combined therapy were higher than MVD of RFA alone therapy slightly, but there was no statistical significance between them (P<0.05) . 5. There was a positive correlation between VEGF and MVD in the combined treatment groups (P<0.01) .Conclusions: 1. Both RFA alone and RFA combined with TAE therapy can induce the apoptosis and inhibit the cell proliferation in 1 week after treatment. 2. Compared with RFA alone , combined therapy can induce more cells to apoptosis and inhibit more cells proliferation , and can get better therapeutic efficacy . 3. Both RFA alone and RFA combined with TAE therapy can effectively inhibit tumor angiogenesis in 1 week after treatment. As for the efficacy of it, combined therapy is parallel with RFA alone. 4. Duing to tumor angiogenesis existed, combined therapy plus anti-angiogenesis drugs may obtain better therapeutic efficacy.