 Brain tumors account for nearly 20 of all childhood malignancies. Of these, gliomas represent 50 of all brain tumors in children and young adults. Gliomas are classically divided into two subtypes - low-grade and high-grade. Low-grade gliomas LGG include pilocytic astrocytomas and diffuse astrocytomas, and high-grade gliomas HGG include anaplastic astrocytoma and glioblastoma multiforme. Although patients with grade I and II tumors have a good prognosis with 5-year overall survival rates of 80-90, those cases that are recurrent, refractory, andor unresectable remain a challenge. The prognosis of children and young adults with recurrent or refractory malignant brain tumors remains poor despite dramatic improvements in treatment over the past few decades, with only a minority achieving long-term survival if recurrence occurs following initial surgical resection and adjuvant chemotherapy. 