Phase I study of fractionated high dose rate brachytherapy for recurrent glioblastoma

This study was done to determine the acute morbidity of fractionated high dose rate brachytherapy for recurrent glioblastoma delivered in three dose levels. Between August 1992 and September 1994, twelve patients with recurrent glioblastoma were treated with high dose rate interstitial brachytherapy in three groups: 25 Gy (two patients), 40 Gy (five patients), and 50 Gy (five patients). Treatment was delivered at 2.5 Gy per fraction twice a day, and at least eight hours apart. The Cancer Therapy Evaluation Program morbidity score was used to assess acute morbidity. One patient in the 25-Gy group had grade 1 morbidity, no patients in the 40-Gy group had any acute morbidity, and two patients in the 50-Gy group had grade 2 morbidity plus one other patient died of presumed meningitis. The rate of infection was two of twelve. The rate of necrosis requiring reoperation was three of twelve. Eight of twelve patients maintained their pretreatment Karnofsky Performance Score at two to three months after treatment. In conclusion, we have determined that brachytherapy treatment of 40 Gy in 2.5 Gy per fraction twice a day is the suitable dose level for future studies.