Comparison of Radiation Therapy Regimens in Combination With Chemotherapy in Treating Young Patients With Newly Diagnosed Standard-Risk Medulloblastoma

DISEASE CHARACTERISTICS:

• Histologically confirmed medulloblastoma located in the posterior fossa

  • Standard-risk disease

• Minimal volume, non-disseminated disease, defined by the following:

  • Residual tumor ≤ 1.5 cm^2 confirmed by MRI with contrast imaging within 21 days after surgery

  • No metastatic disease in the head, spine, or cerebrospinal fluid (CSF) confirmed by both of the following:

    • Enhanced MRI of the spine within 5 days before surgery OR within 28 days after surgery
    • Negative cytological examination of CSF after surgery, but before study enrollment
• Brain stem involvement allowed

PATIENT CHARACTERISTICS:

Age

• 3 to 21 at diagnosis

Performance status

• Karnofsky 50-100% (> 16 years of age) OR
• Lansky 30-100% (≤ 16 years of age)

Life expectancy

• Not specified

Hematopoietic

• Absolute neutrophil count > 1,500/mm^3
• Platelet count > 100,000/mm^3 (transfusion independent)
• Hemoglobin > 10 g/dL (transfusions allowed)

Hepatic

• Bilirubin < 1.5 times upper limit of normal (ULN)
• AST or ALT < 1.5 times ULN

Renal

• Creatinine clearance OR radioisotope glomerular filtration rate ≥ 70 mL/min

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• No prior chemotherapy

Endocrine therapy

• Prior corticosteroids allowed

Radiotherapy

• No prior radiotherapy

Surgery

• See Disease Characteristics