Combination Chemotherapy Followed by Bone Marrow and/or Peripheral Stem Cell Transplantation in Treating Patients With Recurrent Medulloblastoma or CNS Germ Cell Tumors

You may be eligible if

• DISEASE CHARACTERISTICS:
• Diagnosis of recurrent medulloblastoma or CNS germ cell tumor
• * Histologic review of the primary intracranial or spinal cord tumor required
• * Biopsy and reduction of tumor bulk prior to study encouraged but not required
• No more than 1 prior primary therapy (radiotherapy or chemoradiotherapy) and/or 1 prior salvage therapy
• * Patients with progression on salvage therapy ineligible
• Minimal residual disease (tumor bulk no more than 1.5 cm) or in second clinical complete remission (CR)
• Bone marrow infiltration with or without mass lesions or isolated abnormal CSF cytology as the only manifestation of recurrent disease allowed if a clinical CR is first achieved with conventional therapy
• PATIENT CHARACTERISTICS:
• Age:
• 2 to 25
• Performance status:
• Karnofsky 80-100%
• Life expectancy:
• More than 8 weeks
• Hematopoietic:
• Absolute neutrophil count greater than 1,000/mm\^3
• Platelet count greater than 100,000/mm\^3
• Hepatic:
• Bilirubin less than 1.5 mg/dL
• SGPT less than 80 IU
• Renal:
• Creatinine less than 1.2 mg/dL
• Cardiovascular:
• LVEF normal
• Other:
• No infection
• Able to tolerate vigorous hydration
• Not pregnant
• Fertile patients must use effective contraception
• PRIOR CONCURRENT THERAPY:
• Biologic therapy:
• Not specified
• Chemotherapy:
• See Disease Characteristics
• Prior cyclophosphamide or ifosfamide allowed
• Endocrine therapy:
• No concurrent dexamethasone as an antiemetic
• Other concurrent corticosteroids allowed
• Radiotherapy:
• See Disease Characteristics
• Pretransplantation radiotherapy boost allowed
• Surgery:
• See Disease Characteristics
• Pretransplantation surgery allowed
• Other:
• At least 4 weeks since prior therapy except corticosteroids