INTERACTION BETWEEN MICROWAVE-INDUCED BRAIN HYPERTHERMIA AND HIGH-DOSE-RATE RADIATION IN THE BT(4)AN BRAIN GLIOMA IN RATS

The cerebral BT(4)An glioma model in BD IX rats was used to study the effect of hyperthermia given in combination with radiotherapy (thermor adiotherapy) in the treatment of brain tumours. A single treatment wit h high dose rate radiation was given to a local brain field. Local bra in hyperthermia was given at 42.4 degrees C for 45 min by externally a pplied microwaves (700 MHz), immediately before radiotherapy (10 Gy). In a pilot study, thermoradiotherapy increased the median life span wi th 20 days compared to controls, which was significantly better than t hat observed after radiotherapy alone (7 days). In an extended experi ment the corresponding figures for thermoradiotherapy, hyperthermia al one and radiotherapy alone were 12.5, 3.5, and 3.5 days, respectively. Thermoradiotherapy was significantly better than radiotherapy and hyp erthermia alone. There was no acute mortality in these experiments. Ne urological side-effects were infrequent, of slight degree and reversib le. The present study shows that a survival benefit of adding hyperthe rmia to radiotherapy can be achieved without unacceptable neurological side-effects in an animal glioma model.