Interaction of ultrasound with neoplastic tissue. Local effect on subcutaneously implanted Furth-Columbia rat Wilms' tumor

Ultrasonic irradiation was employed by direct administration to the skin overlying subcutaneously implanted Furth-Columbia rat Wilms' tumors. Treated tumors were flattened and excavated and demonstrated no stigmata of hemorrhage or infection. There was a marked decrease in growth rate of the tumors with an increase in survival time of the host. Histologic assessment with the light microscope exhibited a sharp line of demarcation between the necrosed sonicated portion of tumor and the viable intact nonsonicated area of tumor. A blackened area of skin, which was not histologically similar to a burn, was interposed betwwen the site of application of the ultrasound and the necrosed tumor.