Cure of a Solid Tumor by Simultaneous Administration of Microwaves and X-Ray Irradiation

An ionizing radiation therapy technique that enables simultaneous local irradiation and heating of the tumor is described. Microwave energy was used to generate heat within the tissues in order to sensitize a radiation resistant tumor. The system was tested on F1 mice bearing an SV-40 fibrosarcoma in the limb. In successive experiments four types of treatment were compared: (1) control, only anesthetized; (2) heat treatment alone (intratumor temperature of 44°C); (3) radiation alone (800 R); (4) combined treatment by simultaneous heating and X-irradiation. These treatments were given once or twice. No cure was observed by heat treatment alone. A small delay and a few cases of cure resulted by radiotherapy alone. Combined microwave-heating and X-irradiation treatment given once at an early stage of tumor growth resulted in cures of 20% of the mice. When given twice, simultaneous heating and X-irradiation cured 80% of recipients.