Radiosurgery plus the radiation sensitizer etanidazole is being evaluated in a Radiation Therapy Oncology Group trial (RTOG 95-02) as a treatment for recurrent or persistent brain tumors or metastases.
The study will measure acute and late toxicities, tumor response rates, time to tumor progression, and survival rates.
To be eligible for the study patients must have had prior brain irradiation for primary brain tumor or metastasis.
Patients are being randomized to different treatment arms based on tumor diameter: Patients with tumors 20 mm or less in size will receive 24 Gy of radiation in one fraction. Patients with tumors 21 to 30 mm will be treated with 18 Gy in one fraction, and patients with tumors 31 to 40 mm will be given 15 Gy in one fraction.
All patients will receive 12 g/m² of etanidazole given intravenously over a 15-minute period beginning 45 minutes before stereotactic radiation. The study requires 18 patients per treatment arm.
This study is based on RTOG 90-05, which found the maximum tolerable radiosurgery dose to be 24 Gy for tumors 20 mm or less in size, said Dr. Todd Wasserman, chair of the study. "In addition, etanidazole was studied in RTOG 89-06, which determined that 12 g/m² produced very satisfactory blood and tumor levels."