In vivo effects of high-intensity ultrasound on prostatic adenocarcinoma Dunning R3327.

High-intensity ultrasound has been used to treat Dunning R3327 prostatic adenocarcinoma implanted s.c. in Fischer Copenhagen rats. Focused ultrasound was generated with a 1-MHz transducer and energy was provided by a 7.5-kW power amplifier. Seventy-four rats were treated using two different sublines of Dunning tumor. Study 1 dealt with 49 rats with the Mat-Ly-Lu subline, treated with acoustic intensities ranging from 300 to 2750 W/cm2. Of the 49 rats in Study 1, 30 had complete tumor necrosis and 19 had no effect; of the 30 who had complete local tumor necrosis, 14 had local relapse, 9 had distance metastases to lung and nodes without local occurrence, and 7 remained free of tumor and were still alive 12 months after treatment. In Study 2, 25 rats with AT2 subline were treated with an intensity of 820 W/cm2. Similarly for Study 2, there was complete local tumor necrosis in 24 of 25 animals, with local regrowth in 7 of 24 and no recurrence of metastasis in the remaining 16 after a follow-up of 3 months. These results suggested that high-intensity focused ultrasound could be useful for the treatment of small localized cancerous tumors such as low-grade prostate carcinoma.