INTERSTITIAL BRACHYTHERAPY PROCEDURES FOR BRAIN-TUMORS

Promising results have been obtained using brachytherapy in the treatm ent of brain turners. Very low-dose rate brachytherapy (60-100 Gy give n at 0.05-0.10 Gy/h) has been used for low-grade gliomas, resulting in 5- and 10-year survival probabilities of 85% and 83% for pilocytic as trocytomas and 61% and 51% for grade II astrocytomas. Only 2.6% of pat ients had symptomatic radiation necrosis. For faster-growing high-grad e gliomas, temporary im plants delivering about 60 Gy at 0.30-0.60 Gy/ h are generally used. The largest series have reported median survival times of 12-13 months after brachytherapy for recurrent malignant gli omas and 18-19 months after diagnosis of primary glioblastomas treated with external beam radiotherapy and brachytherapy boost. A recent pro spective, randomized trial demon strated significantly improved surviv al for high-grade glioma patients who had brachytherapy boost. However , over 50% of patients who undergo brachytherapy for malignant gliomas require reoperation for tumor progression and/or radiation necrosis. Strategies are under development to improve local control without incr easing radiation toxicity. (C) 1997 Wiley-Liss, Inc.