Histologically confirmed newly diagnosed CNS tumors of any of the following :

   - Medulloblastoma (all histologic subtypes, including medullomyoblastoma and melanotic
   medulloblastoma)

   - Supratentorial primitive neuroectodermal tumor (PNET) (including CNS neuroblastoma or
   ganglioneuroblastoma, medulloepithelioma, and ependymoblastoma)

   - Pineoblastoma

   - Atypical teratoid rhabdoid tumor (ATRT)

   - Choroid plexus carcinoma

   - High grade glioma (including anaplastic astrocytoma, anaplastic oligodendroglioma,
   anaplastic ganglioglioma, pleomorphic xanthoastrocytoma with anaplastic features,
   high-grade astroblastoma , anaplastic pilocytic astrocytoma, malignant glioneuronal
   tumor, glioblastoma multiforme), or gliosarcoma,

   - Ependymoma (including all ependymoma histological variants)

   - Age < 3 years at time of diagnosis for all histological diagnosis. Medulloblastoma
   patients ≥ 3 and < 5years old at diagnosis who have non-metastatic disease with no
   more than 1cm2 of residual tumor are also eligible.

      - Meets criteria for 1 of the following risk groups:

   - Low-risk group:

      - Histologically confirmed nodular desmoplastic medulloblastoma, including
      medulloblastoma with extensive nodularity

         - Focal areas of anaplasia or other atypical features suggesting more
         aggressive phenotype in a tumor otherwise considered nodular desmoplastic
         should be treated on the intermediate-risk group, with final risk
         stratification at the discretion of principal investigator and study
         pathologist

      - No evidence of CNS metastasis 7 to 28 days after surgery by MRI and cytologic
      examination of lumbar cerebrospinal fluid (CSF)

         - Ventricular CSF from a shunt or Ommaya reservoir may be used to rule out M1
         disease when lumbar puncture is medically contraindicated

         - Intermediate-risk group assignment when there is no other evidence of
         metastasis and CSF sampling is not possible

      - Gross total resection, defined as residual tumor or imaging abnormality (not
      definitive for residual tumor) with a size of < 1 cm2 confirmed on postoperative
      CT scan or MRI

      - Brain stem invasion by the tumor in the absence of imaging evidence of residual
      tumor (tumor size < 1 cm2) and otherwise meets criteria for the low-risk group,
      the patient will be classified as low-risk

      - Desmoplastic medulloblastoma patients who are ≥3 -<5 years of age will NOT be
      eligible for the low risk arm of the protocol.

   - Intermediate-risk group:

      - Histologically confirmed nodular desmoplastic medulloblastoma with less than
      gross total resection and no evidence of metastasis

      - Any eligible histologic diagnosis other than desmoplastic medulloblastoma with no
      evidence of CNS metastasis

      - Medulloblastoma patients who are ≥3 and < 5 yrs of age irrespective of histology
      and with no evidence of CNS metastasis

   - High-risk group:

      - Any eligible histologic diagnosis with evidence of CNS metastasis

      - Patients with extraneural metastasis are eligible for treatment on the high-risk
      group

PATIENT CHARACTERISTICS:

   - Lansky performance status ≥ 30 (except for posterior fossa syndrome)

   - WBC > 2,000/mm3

   - Platelets > 50,000/mm3 (without support)

   - Hemoglobin > 8 g/dL (with or without support)

   - ANC > 500/mm3

   - Serum creatinine < 3 times upper limit of normal (ULN)

   - ALT < 5 times ULN

   - Total bilirubin < 3 times ULN

PRIOR CONCURRENT THERAPY:

   - See Disease Characteristics

   - No more than 31 days since prior definitive surgery

   - No prior radiotherapy or chemotherapy other than corticosteroid therapy