DISEASE CHARACTERISTICS:

• Histologically confirmed newly diagnosed primary CNS germ cell tumor OR
• Serum or cerebrospinal fluid (CSF) elevation of alpha-fetoprotein (AFP) or beta-human chorionic gonadotropin (beta-HCG) greater than 50 ng/mL

• Low-risk disease:

  • Histologically proven pure germinoma
  • Localized, nonmetastatic disease
  • Normal CSF
  • Normal serum tumor markers

• Intermediate-risk disease:

  • Histologically proven germinoma
  • Beta-HCG-positive syncytiotrophoblastic giant cell component AND/OR
  • CSF elevation of beta-HCG to less than 50 ng/mL

• High-risk disease:

  • Histologically proven choriocarcinoma, endodermal sinus tumor, or embryonal carcinoma
  • Elevated serum and/or CSF AFP OR
  • Elevated serum beta-HCG OR
  • Elevated CSF beta-HCG greater than 50 ng/mL OR
  • Disseminated disease by MRI and/or CSF cytology

PATIENT CHARACTERISTICS:

Age:

• Any age

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Bilirubin less than 2.0 mg/dL
• Indirect hyperbilirubinemia due to Gilbert's syndrome is allowed
• AST and ALT less than 5 times upper limit of normal

Renal:

• Creatinine clearance greater than 60 mL/min

Cardiovascular:

• Cardiac function normal by echocardiogram
• No myocardial infarction or ischemia in patients over 30 years
• Fractional shortening greater than 30%

Other:

• No unacceptable morbidity of organ systems outside the CNS
• Not pregnant
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No prior chemotherapy

Endocrine therapy:

• No concurrent corticosteroids administered solely for antiemesis during study chemotherapy

Radiotherapy:

• No prior cranial radiotherapy

Surgery:

• Not specified