Combined ultrasound and radiation therapy treatment of human superficial tumors.

Ultrasound, used to generate local tumor hyperthermia, was combined with radiation therapy in a pilot study to determine efficacy and toxicity of this combined-modality therapy. Twenty-one lesions in eighteen patients were treated at graded doses from 2400-4000 rads (24-40 Gy) with ultrasonic hyperthermia administered immediately prior to irradiation at 43.5 degrees C +/- 0.5 degrees C for one hour. The overall response rate was 100%, with a 62% complete response rate. Of those lesions that responded completely and were followed for periods of three to twenty-two months, there have been no recurrences of the lesions treated with the combined modalities. The response rate for control unheated lesions in the same patient in the same radiation field was markedly lower (30% overall and no complete responses). Heat treatment alone in the same patients also showed lower response rates (50% overall and 10% complete) with a short response duration. Toxicities were minimal, consisting of one case with long-term treatment-associated sequelae. It is concluded that this combined modality of therapy is safe and effective where applied in human superficial tumors and that further development is warranted.