INFLUENCE OF HIGH-INTENSITY FOCUSED ULTRASOUND ON THE DEVELOPMENT OF METASTASES

Objective: The hypothesis that exposure of a solid tumor to high-inten sity focused ultrasound (HIFU) could lead to an increase of metastases was investigated in an animal model. Methods: The highly metastatic A T-6 Dunning R3327 rat prostate cancer subline was implanted into the h ind limb of Fisher-Copenhagen rats and was exposed to 1 pulse/mm(2) tu mor (acoustical power 1,000 W/cm(2)) delivered by an experimental mach ine (Ablatherm, Technomed, France), or the animals were sham treated, as soon as the tumor had reached a volume of 175-225 mm(3), The tumor- bearing leg was amputated 24 h later and the number of metastases exam ined 12 weeks thereafter at autopsy. Results: Metastases were seen in 3 (23%) of the 13 animals exposed to HIFU and in 4 (25%) of the 16 sha m-treated animals; this is not significantly different. There was also no significant difference in weight of the lungs that contained metas tases between sham-treated and HIFU-treated animals, Conclusion: Metas tatic spread of animal tumors with a high metastatic potential is not enhanced by HIFU exposure.