Objective:To evaluate the safety of high intensity focused ultrasound(HIFU) for the treatment of implanted rabbit breast tumor.Methods:Forty New England rabbits were randomly divided into the following groups:HIFU treatment group(20)

surgery group(10) and control group(10).HIFU ablation was performed at focal peak intensity 11500W/cm with a frequency of 1.6MHz in HIFU group.In surgery group all animals underwent lumpectomy.The animals in control group underwent pseudo-irradiation.The sonograms of target tumor were assessed before and immediately after HIFU ablation.The treated tumor was removed immediately after HIFU

and the lesion was measured by gross examination.Routine serum chemistry examination including hepatic

renal function tests

and serum electrolytes in all animals were performed before and at 1st

3rd

5th and 7th days after treatment.Also tumor metastases were observed after treatment.Results:The gray-scale of target tumors on ultrasound image was low before HIFU and increased immediately after HIFU irradiation.The hyperechoic location was the same as the lesion observed by gross observation.The necrotic lesion completely covered the tumor.No significant differences were observed in hepatic

renal function tests

and serum electrolytes before and after therapy in HIFU group.And these indices were not significantly different in HIFU treatment group

surgery group and control group

respectively.The metastatic rates of HIFU treatment group and surgery group were 20% and 30% respectively.They were significantly different from that of control group(100%

P<0.05).Conclusion:HIFU could precisely and effectively destroy the implanted rabbit breast tumor with guidance of ultrasound imaging.Because it does not increase the metastatic rate of tumor and affect the function of liver and kidney of animals

HIFU is safe for the treatment of breast carcinoma.