RATIONALE: Drugs used in chemotherapy, such as carboplatin and vincristine, work in different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage tumor cells. Combining carboplatin and vincristine with radiation therapy followed by adjuvant chemotherapy may kill more tumor cells.

PURPOSE: Randomized phase II trial to study the effectiveness of combination chemotherapy plus radiation therapy followed adjuvant chemotherapy in treating young patients who have newly diagnosed high-risk CNS embryonal tumors.

OBJECTIVES:

• Determine the feasible dose and duration of carboplatin combined with craniospinal and local radiotherapy and adjuvant chemotherapy in children with newly diagnosed, high-risk CNS embryonal tumors (Phase I completed as of 11-25-03).
• Determine the feasibility of administering cyclophosphamide and vincristine with or without cisplatin after concurrent carboplatin, vincristine, and radiotherapy in these patients.
• Determine the overall and individual toxicity rates of this regimen in these patients.
• Determine the complete response rate in patients treated with this regimen.
• Obtain preliminary estimates of event-free survival of patients treated with this regimen.
• Determine the prognostic significance of enhancing tumor after completion of radiotherapy on event-free survival of these patients.

OUTLINE: This is a pilot, dose-escalation study of carboplatin. (Phase I completed as of 11-25-03.)

Within 31 days of definitive surgery, all patients receive vincristine IV weekly for 6 weeks and carboplatin IV over 15-20 minutes (after completion of vincristine infusion) 5 days a week for 6 weeks. Patients undergo radiotherapy (1-4 hours after carboplatin infusion) 5 days a week for 6 weeks.

Cohorts of 6-12 patients receive escalating doses of carboplatin until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose at which no more than 3 of 12 patients experience dose-limiting toxicity. (Phase I completed as of 11-25-03.)

At 6 weeks after completion of radiotherapy, patients are assigned to arm II for adjuvant/maintenance chemotherapy. (Arm I closed to accrual as of 11-25-03.)

• Arm I (closed to accrual as of 11-25-03): Patients receive cyclophosphamide IV over 1 hour on days 0 and 1, vincristine IV on days 0 and 7, and filgrastim (G-CSF) IV or subcutaneously (SC) beginning on day 2 and continuing for at least 10 days until blood counts recover.
• Arm II: Patients receive cyclophosphamide IV over 1 hour on days 1 and 2, vincristine IV on days 0 and 7, cisplatin IV over 6 hours on day 0, and G-CSF IV or SC beginning on day 3 and continuing for at least 10 days until blood counts recover.

In both arms, adjuvant/maintenance chemotherapy repeats every 4 weeks for 6 courses.

Patients are followed every 3 months for 8 months, every 4 months for 1 year, every 6 months for 2 years, and then annually thereafter.

PROJECTED ACCRUAL: A total of 162 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically proven high-risk CNS embryonal tumors, including:

  • Primitive neuroectodermal tumors
  • Atypical teratoid/rhabdoid tumor
  • Medulloblastoma
  • Desmoplastic medulloblastoma
  • Ependymoblastoma
  • Medullomyoblastoma
  • Spongioblastoma
  • Spongioblastoma polare
  • Primitive polar spongioblastoma
  • Neuroepitheliomatous neoplasms
  • Medulloepithelioma
  • Neuroblastoma
  • Pineoblastoma

• No bone marrow involvement or bone metastases

• No M4 disease

• M3 disease must have evidence of tumor on spinal MRI

PATIENT CHARACTERISTICS:

Age:

• 3 to 21 at diagnosis

Performance status:

• Not specified

Life expectancy:

• At least 8 weeks

Hematopoietic:

• Absolute neutrophil count greater than 1,500/mm^3
• Platelet count at least 100,000/mm^3 (transfusion independent)
• Hemoglobin at least 10.0 g/dL (packed red blood cell transfusions allowed)

Hepatic:

• Bilirubin less than 1.5 mg/dL
• SGOT/SGPT less than 2.5 times normal

Renal:

• Creatinine less than 1.5 times upper limit of normal OR
• Creatinine clearance or radioisotope glomerular filtration rate at least 70 mL/min

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No prior chemotherapy

Endocrine therapy:

• Not specified

Radiotherapy:

• No prior radiotherapy

Surgery:

• Prior definitive surgery allowed