DISEASE CHARACTERISTICS:

• Histologically confirmed newly diagnosed CNS tumor of the following types:

  • High grade glioma (HGG) of one of the following histologies:

    • Anaplastic astrocytoma (grade III)
    • Glioblastoma multiforme (grade IV)
    • Gliosarcoma
    • Primary spinal cord malignant glioma

  • Diffuse intrinsic pontine glioma (DIPG)

    • Diagnosed by gadolinium-enhanced MRI
    • At least 2/3 of tumor situated in the pons AND tumor clearly originated in the pons
    • No diffuse leptomeningeal disease

    • No tumors with features not typical of diffuse intrinsic brainstem glioma, including any of the following:

      • Dorsally exophytic brainstem glioma
      • Cervico-medullary junction tumor
      • Focal low-grade glioma of the midbrain or brainstem
    • No diffuse brainstem enlargement due to neurofibromatosis
• No primary brain stem malignant glioma
• No M+ disease (CSF positive for tumor or metastatic disease)
• Must begin study radiotherapy within 6 weeks after surgical resection (for HGG patients) or diagnosis (for DIPG patients)

PATIENT CHARACTERISTICS:

Age:

• 3 to 21

Performance status:

• Karnofsky 50-100% OR
• Lansky 50-100%

Life expectancy:

• At least 2 months

Hematopoietic:

• Absolute neutrophil count at least 1,000/mm^3
• Platelet count at least 100,000/mm^3*
• Hemoglobin at least 10.0 g/dL* NOTE: *Transfusion independent

Hepatic:

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• SGOT or SGPT less than 2.5 times ULN

Renal:

• Creatinine no greater than 1.5 times ULN

Other:

• No other concurrent malignancy
• Concurrent seizure disorder allowed if well controlled on anticonvulsants
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 2 months after completion of study treatment

PRIOR CONCURRENT THERAPY:

Biologic:

• No concurrent routine cytokine support

Chemotherapy:

• Not specified

Endocrine therapy:

• No concurrent corticosteroids except for increased intracranial pressure in patients with CNS tumors

Radiotherapy:

• See Disease Characteristics

Surgery:

• See Disease Characteristics

Other:

• No prior therapy for HGG or DIPG