Clinical evaluation of combined hyperthermia and radiation therapy for radioresistant superficial malignant tumors.

From January 1985 to October 1986, 25 tumors in 23 patients were treated with combined hyperthermia and radiation therapy. All of these tumors were recurrent tumors after initial radiation therapy, and were presumed to be radioresistant tumors on the basis of histological findings and poor response at 30-40 Gy. Heat was delivered using the radiofrequency of 13.56 MHz at 500 W or 1000 W. In combination with radiation therapy, hyperthermia was given at 42 degrees-43 degrees C for 30 minutes per fraction once a week for a total of four to five fractions (Protocol 1), or twice a week for a total of six to 10 fractions (Protocol 2). Hyperthermia once a week was as effective as twice a week. Small and diffuse tumors showed better results. Combined therapy was better than irradiation alone for suppression of these tumors. The adverse effects included three subcutaneous fat necroses with an associated lipoma in one case and three skin ulcers.