[Radiofrequency hyperthermia in malignant brain tumors: clinical trials]

Local hyperthermia using 13.56-MHz radiofrequency (RF) capacitive heating was evaluated in 19 patients with malignant brain tumor. Intraoperative heating was performed in 4 patients. RF applicators were placed on the cerebral convexity and medial surface with the tumor between them. RF power was controlled so as to maintain the brain temperature below 40 degrees C. Under these conditions, the highest temperature of each tumor varied from 44 to 52 degrees C. After heating alone for about 60 min, 3 tumors showed regression on CT scan. Extracranial heating was performed in 15 patients with cerebral glioblastoma. RF applicators were placed on the scalp and applied to diametrically opposite sides of the tumor after bilateral craniectomy not smaller than the size of the applicator. The heating was performed for about 60 min at each session and repeated twice a week for a total of 4 to 10 times in combination with radiation and ACNU-chemotherapy. The brain temperatures were maintained below 42 degrees C. The highest temperatures of the tumor varied from 42 to 46 degrees C. Seven of 13 evaluable tumors on CT scan showed regression after the treatment. Low-density lesions appeared transiently in the brains of 2 patients, located in the RF field. In conclusion, RF capacitive heating can be applied to human malignant cerebral tumors.