Study of Systemic and Spinal Chemotherapy Followed by Radiation for Infants With Brain Tumors

Inclusion/Exclusion Criteria:

* Age: \< 3 years.
* Histology: Patient must have a histologically confirmed primary intracranial CNS medulloblastoma/PNET or other embryonal tumor (medulloepithelioma, ependymoblastoma, neuroblastoma, pineoblastoma), atypical teratoid/rhabdoid tumor, intracranial germ cell tumor, or choroid plexus carcinoma. Patients with M+ ependymoma are also eligible.
* Performance Status: Karnofsky or Lansky \>= 30%
* Bone Marrow Function: All patients must have a Hgb \>= 10 g/dl, ANC \>= 1,500/mm3, and a platelet \>= 100,000/mm3. If the patient has a positive bone scan, then a pretreatment bone marrow aspirate and biopsy must be free of tumor.
* Hepatic/Renal Function: All patients must have adequate hepatic (total bilirubin \< 1.5 mg/dl, SGPT \< 5x normal), and renal (normal serum creatinine for age or technetium clearance \> 40/ml/min/m2) function.
* Prior Therapy: Patients may not have received prior radiotherapy or chemotherapy, with the exception of steroids. Patients must not be receiving any other investigational agents. (Patients may receive investigational agents for supportive care 30 days after completion of all mafosfamide therapy.)
* Surgery: Patients must begin protocol therapy within 35 days of definitive surgery.
* Central Line: Patients must be willing to have a central line.
* CSF flow: Patients must be willing to have a CSF flow study to determine whether or not they will receive intrathecal chemotherapy. Patients without a VP or VA shunt must be willing to have an Ommaya reservoir if their CSF flow study does not show any evidence of obstruction to or compartmentalization of flow. Patients with obstruction to or compartmentalization of CSF flow on their initial flow study must be willing to have a repeat flow performed within the initial 10 weeks of induction therapy, ideally during weeks 8-10. If a repeat flow study shows resolution of obstruction or compartmentalization, patients are expected to begin intrathecal mafosfamide during Regimen 1 course 2 of therapy. Patients without a VP or VA shunt who have resolution of normal flow should additionally have an Ommaya reservoir placed.