Interstitial thermoradiotherapy.

The results of a phase I clinical trial in which heat was combined with interstitial (low dose rate) radiation are described with emphasis on response and technical and physical aspects of heating. We treated 25 patients (27 lesions) using interstitial implants to locally recurrent, accessible tumors heated by radiofrequency currents to 43 degrees -45 degrees C for 30 minutes, with needle guides as electrodes. They were subsequently irradiated with either 192Ir or 226Ra. All patients had failed previous conventional treatments including surgery, chemotherapy, and, in most, near tolerance doses of irradiation. In all but one, a single hyperthermic treatment was given and the average dose of low dose irradiation was under 3,000 rad over 60 hours. No patient failed to respond, 63% achieved a complete disappearance of tumor in the treated volume, and 37% had partial response (50% less than volume reduction less than 100%). Duration of response was from 2 to 30 months, and no patient showed regrowth at the site treated. Normal tissue complications were minimal. Interstitial thermoradiotherapy is both a safe and an effective means of treatment in advanced or recurrent accessible disease.