Combined radiation and hyperthermia in superficial human tumors

Hyperthermia (42--43 C) appears to potentiate the effects of radiation therapy in experimental tumor models. In addition, some studies indicate that tumors may be sensitized to a greater extent than normal tissue. This study was designed to test whether the effectiveness of irradiating human tumors was enchanced significantly by concomitant heating. We also examined skin to see if heating enhanced the response to radiation of normal tissues. Nineteen patients with multiple metastatic superficial tumor masses of various histologies were studied. All were considered incurable and an independent clinical decision had been made to irradiate for palliation. Two or more masses in the same patient were matched for size and location, so that one of the patient's own tumors was a control to monitor the effect of irradiation alone. On each patient the tumors were treated with identical fractions and to the same total dose of radiation. One of the matched nodules was given hyperthermia (43 C) for 15 minutes before and 30 minutes after each radiation fraction. The response of the tumor that received radiation alone was compared with that of the tumor receiving hyperthermia and radiation. In seven of 15 evaluable patients the tumor that received heat in addition to radiation had a greater objective response than the tumor receiving radiation alone (P < .065). Of the remaining eight patients, four had complete tumor regression in both areas without later regrowth, two failed to respond in either area, and two partially responded in both areas. Two patients had increased cutaneous reaction to radiation in the heated area; one of these was a severe desquamative reaction, which conformed to the size and shape of the ultrasound field. These results suggest that hyperthermia improves the objective response to radiation in some human tumors; in two cases it appeared to sensitize skin as well.