Hyperthermia in combination with radiotherapy: a review of five years experience in the treatment of superficial tumors.

Facilities for regional tumor hyperthermia has been in use at RPMI since 1976, and have been routinely used to treat patients according to protocol since 1977. Hyperthermia delivery has been exclusively by microwave using 434 MHz, 915 MHz and 2450 MHz. Greatest success at reaching tumor temperatures of 43-44 degrees C with minimal skin heating was obtained using 915 MHz. The majority of the patients were treated with this frequency. Approximately 125 patients have been treated and 70 have achieved completion of therapy and follow-up. Follow-up has been at least one month and several patients have been followed for one to two years. Initially, for entry into the hyperthermia protocol, patients were required to have three or more lesions. One lesion on each patient was treated with 800 rad fractions repeated three times on a 72 hour schedule. The second lesion was treated with 700 rad fractions and the third with 500 rad plus hyperthermia on the same schedule. Twelve patients with multiple melanoma lesions completed this study. One of 12 patients showed no response to the combination of hyperthermia plus radiotherapy, while four showed no response to radiotherapy alone. Of eight patients who survived three months, all lesions treated by hyperthermia plus radiotherapy responded completely, while only five lesions treated by radiotherapy alone so responded. In a second study, 58 patients with superficial tumors were treated by a protocol where hyperthermia was added to optimal conventional radiotherapy. Of the total, 43 patients had complete tumor response at follow-up varying from one month to 18 months. A subgroup of 24 of these patients had two lesions, one of which was treated with hyperthermia in addition to radiotherapy while the other served as control, receiving radiotherapy only. Nineteen lesions demonstrated complete response to hyperthermia plus radiotherapy, while only 14 of the controls had complete response. None of the lesions treated with hyperthermia responded less well than those treated by radiotherapy alone. Morbidity, as measured by skin reaction, was rarely increased in the heated field.