Abstract: Objective To investigate the efficacy of combination of vincristine,apixamycin and cyclophosphamide （CAO chemotherapy regimen） combined with high frequency focused ultrasound ablation in the treatment of children with hepatoblastoma （HB） at stage III/IV.Methods The clinical data of 34 children with HB at stage III and IV recruited in our hospital between December 2010 and January 2016 were analyzed retrospectively. Out of them,16 patients t were treated with combination of CAO chemotherapy regimen and high-frequency focused ultrasound ablation,and 18 patients were treated with CAO chemotherapy regimen alone. All the children were followed-up for 24 months. The biochemical indicators,tumor relief,adverse reactions of chemotherapy and the outcomes of patients were compared between the two groups.Results At the end of three-month treatment,serum AFP level in the combination group was （43.2±5.4） μg/L,serum ALT level was （93.5±26.3） U/L,and serum AST level was （91.2±30.2） U/L,significantly lower than （55.3±6.2） μg/L,（197.1±57.8） U/L and （213.7±66.2） U/L in the control （P<0.05）,while blood Hb levels in the two groups were not significantly different （P>0.05）;the tumor remission rate in the combination group was 81.3%,significantly higher than 61.1% in the control （P<0.05）;the incidence of side effect in the combination was 18.8%,not significantly different compared to 27.8% in the control （P>0.05）;at the end of 24 month followed-up,the fatality rate in the combination group was 6.3%,not significantly different compared to 11.1% in the control（P>0.05）,however,the recurrence rate of intrahepatic tumor was 13.3% in combination group,significantly lower than 25.0% in the control（P<0.05）. Conclusion The CAO chemotherapy regimen combined with high-frequency focused ultrasound ablation in the treatment of children with stage III and IV HB might be efficient,which delay the tumor growth and reduce the recurrence rate after treatment.

Key words: Hepatoblastoma, Chemotherapy, High-frequency focused ultrasound ablation, Response, Survival