RATIONALE: Specialized radiation therapy that delivers radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue.

PURPOSE: This phase II trial is studying how well radiation therapy works in treating young patients with gliomas.

OBJECTIVES:

Primary

• Determine the marginal-failure rate in young patients with low-grade gliomas treated with reduced-field conformal radiotherapy.

Secondary

• Determine the progression-free survival, event-free survival, and overall survival rates of young patients treated with this regimen.
• Determine quality of life of patients treated with this regimen.
• Correlate MIB-1 labeling index with progression-free survival and overall survival of these patients.

OUTLINE: This is a multicenter study.

Patients undergo reduced-field conformal radiotherapy 5 days a week for 6 weeks in the absence of disease progression or unacceptable toxicity.

Quality of life is assessed at baseline or 6 weeks after completion of study treatment and then at 2 and 5 years (closed as of 10/27/2010).

After completion of study treatment, patients are followed every 3 months for 2 years, every 6 months for 2 years, and then annually thereafter.

DISEASE CHARACTERISTICS:

• Histologically confirmed* low-grade glioma, including any of the following:

  • Juvenile pilocytic astrocytoma (JPA) or pleomorphic JPA

  • Diffuse astrocytoma, including any of the following subtypes:

    • Fibrillary astrocytoma
    • Gemistocytic astrocytoma
    • Subependymal giant cell astrocytoma
    • Pleomorphic xanthoastrocytoma

  • Low-grade oligoastrocytoma

  • Low-grade oligodendroglioma

  • Low-grade glioma not otherwise specified NOTE: *Patients with chiasmatic lesions who have contiguous extension of tumor into other regions of the visual pathway by CT scan or MRI are eligible without histopathologic confirmation; repeat biopsy required for patients with recurrent tumors that enhance but whose initial tumor did not

• Measurable disease by radiography

• Meets any of the following criteria:

  • Progressive nonresectable disease

    • Any location in the brain

  • Patients with a less than gross total resection are eligible provided they are symptomatic from their tumor OR the risk from neurologic impairment with progression is high enough to warrant immediate treatment

  • Has undergone biopsy only

• Must have received ≥ 1 course of prior chemotherapy (for patients < 10 years of age)

  • Prior chemotherapy optional (for patients ≥ 10 years of age)

• No type-1 neurofibromatosis

• No evidence of leptomeningeal dissemination

PATIENT CHARACTERISTICS:

Age

• 3 to 20

Performance status

• ECOG 0-2 OR
• Karnofsky 50-100% (for patients > 16 years of age) OR
• Lansky 50-100% (for patients ≤ 16 years of age)

Life expectancy

• At least 1 year

Hematopoietic

• Absolute neutrophil count ≥ 1,000/mm^3
• Platelet count ≥ 100,000/mm^3 (transfusion independent)
• Hemoglobin ≥ 10.0 g/dL (transfusions allowed)

Hepatic

• Not specified

Renal

• Not specified

Other

• Not pregnant
• Negative pregnancy test
• Fertile patients must use effective contraception
• Not in status epilepticus, coma, or requiring assisted ventilation prior to study entry
• Patients with a seizure disorder are eligible provided they are on anticonvulsants AND disease is well controlled

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• See Disease Characteristics
• Recovered from prior chemotherapy
• No concurrent chemotherapy

Endocrine therapy

• Concurrent dexamethasone allowed provided patient has been on a stable dose for ≥ 2 weeks prior to study entry
• Concurrent dexamethasone allowed for symptoms of increased intracranial pressure

Radiotherapy

• No prior radiotherapy

Surgery

• See Disease Characteristics

Other

• No other concurrent anticancer therapy