Inclusion Criteria

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