CLINICAL-EXPERIENCES WITH LOCAL MICROWAVE HYPERTHERMIA

A group of 38 patients who failed definitive radiotherapy and chemotherapy were treated with 915 and 2450 MH microwave hyperthermia to observe normal tissue tolerance and therapeutic responses. Superficial and mesurable lesions were selected. Thirty-seven courses were given with radiation and 11 courses were given alone. When hyperthermia was combined with radiation, complete clinical regression occurred in 41% (15/37) of patients and partial regression in 37% (14/37); however with hyperthermia alone, complete regression occurred in 18% (2/11) of patients and partial regression in 18% (2/11). Moderate local tumor hyperthermia (42.5.degree. C) following low dose irradiation (1800-2700 rad) resulted in significant responses in recurrent tumors in previously irradiated areas. The maximum temperature achieved during a course of treatment appeared to correlate with tumor responses. A relationship existed betweeen radiation dose and tumor response. There was no relationship between radiation dose and thermal side effects. Thermal dosimetry remained an outstanding problem for clinical hyperthermia, in part because of inadequacy of heat delivery and measurement systems and in part because of patient variations in terms of tolerance to heat and tumor physiological changes with fractions of hyperthermia. Side effects of thermal blistering and burns were correlated with maximum temperatures attained during heat treatments. They were tolerable by patients and can be decreased by appropriate skin cooling in some patients. Further protocol studies are needed to determine the optimal temperature/radiation dosage, treatment schedules and sequences and treatment techniques.