DISEASE CHARACTERISTICS:

• Histologically confirmed malignant, newly diagnosed brain tumor

Regimen A:

• Posterior fossa medulloblastoma/primitive neuroectodermal tumor (PNET):

  • All stages, under 3 years at diagnosis OR
  • High stage (local residual tumor postoperatively and/or neuraxis or extraneural dissemination), 3-10 years at diagnosis

• Supratentorial PNET, pineoblastoma, cerebral neuroblastoma, ependymoblastoma, medulloepithelioma, medullomyoblastoma:

  • All stages, under 10 years at diagnosis

• Brainstem PNET:

  • All stages, irrespective of extent of resection, under 10 years at diagnosis

• Ependymoma or anaplastic ependymoma:

  • All stages, any location (except primary spinal cord ependymoma), under 3 years at diagnosis OR
  • Local residual tumor postoperatively and/or neuraxis dissemination, any location, 3-10 years at diagnosis

• Supratentorial ependymoma:

  • All stages, irrespective of extent of resection, under 10 years at diagnosis, excluding gross totally resected (confirmed by postoperative MRI) low grade ependymoma not invading the ventricular system

• Metastatic retinoblastoma:

  • Previously untreated (except for cryosurgery or laser surgery), under 10 years at presentation of metastatic disease

• Primary atypical teratoid/rhabdoid tumors of the CNS:

  • Under 10 years at diagnosis

• Choroid plexus carcinoma:

  • Incompletely resected, all sites, under 10 years at diagnosis

Regimen C:

• Anaplastic astrocytoma, glioblastoma multiforme, anaplastic oligodendroglioma, anaplastic ganglioglioma, other anaplastic mixed gliomas:

  • Under 10 years at diagnosis

• Diffuse intrinsic pontine tumors:

  • Unbiopsied, under 10 years at diagnosis

The following diagnoses are not eligible:

• Myxopapillary ependymoma of the spinal cord, low grade brainstem astrocytoma, primary CNS lymphoma or solid leukemic lesion (i.e., chloroma, granulocytic sarcoma), or primary CNS germ cell tumor

PATIENT CHARACTERISTICS:

Age:

• Under 10 at diagnosis

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Bilirubin less than 1.5 mg/dL
• SGPT less than 2.5 times upper limit of normal

Renal:

• Creatinine clearance greater than 60 mL/min

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No prior chemotherapy

Endocrine therapy:

• Prior corticosteroids allowed
• No concurrent corticosteroids for the sole purpose of antiemesis

Radiotherapy:

• No prior radiotherapy

Surgery:

• See Disease Characteristics
• Recovered from prior surgery