Evaluation of high-intensity therapeutic ultrasound irradiation in the treatment of experimental hepatoma.

A study evaluating the efficacy of high-intensity therapeutic ultrasound (HITU) as a treatment modality in experimental hepatoma is reported. Morris hepatoma (3924) 1 x 10(6) cells were transferred subcutaneously into 40 male ACI rats (weight, 150 to 200 g). Animals were divided into four experimental groups: group 1 (n = 10) consisted of untreated controls; group 2 (n = 10) received intraperitoneal cyclophosphamide 50 mg/kg as a single dose; group 3 (n = 10) underwent HITU only; and group 4 (n = 10) received both chemotherapy (as in group 2) and HITU (as in group 3). HITU was administered with a 5.5-cm diameter 4-MHz quartz transducer creating a continuous wave with 400 W/cm2 focal intensity. The entire tumor was irradiated in 1-mm increments (horizontal and vertical) using treatment cycles of 4 seconds on and 11 seconds off. Total body weight and tumor volume were measured on the day of treatment, and 4 weeks later. At 4 weeks, the animals were killed, the tumor was excised and weighed, and tumor volume was determined. Tumor volume in all treated animals (groups 2, 3 and 4) was significantly smaller than in controls (P less than .001) at 4 weeks, and tumor volume for animals in group 4 was significantly smaller than for those in groups 2 and 3 (P less than .01). These data indicate that HITU significantly reduces tumor size when compared with control rats with Morris hepatoma. A synergistic effect of chemotherapy and HITU was observed and resulted in an enhanced tumor response and reduction of tumor size.(ABSTRACT TRUNCATED AT 250 WORDS)