RATIONALE: Drugs used in chemotherapy use 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. It is not yet known whether undergoing surgery plus radiation therapy is more effective with or without chemotherapy for primitive neuroectodermal tumors of the CNS.

PURPOSE: Randomized phase III trial to compare the effectiveness of surgery plus radiation therapy with or without chemotherapy in treating patients who have primitive neuroectodermal tumors of the CNS.

OBJECTIVES: I. Determine whether chemotherapy utilizing carboplatin, vincristine, cyclophosphamide, and etoposide improves the prognosis for children with primitive neuroectodermal tumors of the central nervous system when given after surgery and before radiotherapy. II. Assess prospective factors that may determine ultimate prognosis in this patient population. III. Determine the quality of survival of these patients on both treatment regimens.

OUTLINE: This is a randomized study. Patients undergo surgical removal of the primary tumor. Following surgery, patients are randomized to receive radiotherapy alone (arm I) or chemotherapy followed by radiotherapy (arm II). Arm I: Patients begin receiving radiotherapy as soon as possible after surgery, within 28 days. Radiotherapy is administered 5 times a week for 6 weeks. Arm II: Within 28 days of surgery, patients receive vincristine IV on days 1, 7, 14, 21, 28, 35, 42, 49, 56, and 63. Carboplatin IV is administered over 1 hour on days 1, 2, 42, and 43. Etoposide IV is administered over 1 hour on days 1-3, 21-23, 42-44, and 63-65. Cyclophosphamide IV is administered over 4 hours on days 21 and 63. As soon as possible after chemotherapy, patients receive radiotherapy as in arm I. Quality of life is assessed every 3 months for the first year and annually thereafter. Patients are followed every 6 weeks for the first year, every 3 months for the second year, every 4 months for the third year, and every 6 months thereafter.

PROJECTED ACCRUAL: A total of 230 patients (115 per treatment arm) will be accrued for this study.

DISEASE CHARACTERISTICS: Histologically proven primitive neuroectodermal tumors of the central nervous system No metastatic disease within or outside the central nervous system Must have survived 1 week following surgery Postoperative CT scan and myelogram required

PATIENT CHARACTERISTICS: Age: 3 to 16 Performance status: Not specified Life expectancy: Not specified Hematopoietic: No concurrent hematological disorder Hepatic: Not specified Renal: Renal dysfunction allowed Other: No prior history of malignant disease

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Not specified Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: See Disease Characteristics