Irinotecan Followed by Radiation Therapy and Temozolomide in Treating Children With Newly Diagnosed Brain Tumor

OBJECTIVES: * Evaluate the efficacy of adjuvant irinotecan in children with newly diagnosed high grade gliomas, brain stem glioma, or high risk grade II astrocytomas in terms of complete and partial response rate in patients with postoperative measurable disease, and in terms of the rate of freedom from recurrence in patients with no postoperative measurable disease. * Determine the 3 year overall and progression free survival rates in this patient population when treated with adjuvant irinotecan followed by radiotherapy and temozolomide. * Assess the hematopoietic toxicity of temozolomide following local radiotherapy in this patient population. OUTLINE: Patients receive postoperative irinotecan IV over 60 minutes daily for 5 days on weeks 1-2. Treatment repeats every 3 weeks for 2 courses. Following completion of irinotecan and if appropriate, patients may undergo a second surgical resection. Within 2 weeks following completion of chemotherapy or within 4 weeks of following a second resection, patients receive image guided external beam radiotherapy 5 days per week for 6 weeks. Patients with residual tumor less than 3.5 cm in maximal diameter may undergo boost radiosurgery. At 4 weeks following completion of radiotherapy, patients receive oral temozolomide for 5 days. Treatment repeats every 3 weeks for 6 courses. Patients are followed every 3 months for 2 years, then every 4 months for 3 years. PROJECTED ACCRUAL: A total of 50 patients will be accrued for this study within 5 years.