Combination Chemotherapy With or Without Etoposide Followed By an Autologous Stem Cell Transplant in Treating Young Patients With Previously Untreated Malignant Brain Tumors

OBJECTIVES: Primary * Determine the 2-year event-free survival (EFS) and overall survival (OS) of pediatric patients with previously untreated nondisseminated medulloblastoma (\< 4 years of age), disseminated medulloblastoma (\< 10 years of age), or noncerebellar primitive neuroectodermal tumors (PNET) (disseminated or non-disseminated) treated with induction chemotherapy followed by consolidation with myeloablative chemotherapy and autologous hematopoietic stem cell rescue. * Determine the toxicity of this regimen in these patients. * Determine the mortality of patients treated with this regimen. Secondary * Determine the complete and partial response rates after completion of induction chemotherapy in these patients stratified according to pathology (medulloblastoma vs noncerebellar PNET vs high-grade gliomas vs atypical teratoid/rhabdoid tumors vs choroid plexus carcinomas and atypical papillomas vs ependymomas). * Describe the EFS and OS of these patients stratified according to additional diagnoses (atypical teratoid/rhabdoid tumors vs choroid plexus carcinomas and atypical choroid plexus papillomas vs ependymomas vs high-grade gliomas). * Describe the time to progression and patterns of relapse in these patients stratified by diagnosis and radiotherapy received (\< 6 years of age with evidence of no residual tumor pre-transplant and no post-transplant consolidation radiotherapy vs \< 6 years of age with residual tumor present pre-transplant treated with post-transplant consolidation radiotherapy vs \> 6 years of age treated with post-transplant consolidation radiotherapy). * Determine the neuropsychometric function, endocrinologic function, and physical growth in these patients stratified according to radiotherapy received (none vs reduced-volume craniospinal radiotherapy vs focused local-field radiotherapy). OUTLINE: This is a pilot study. Patients are stratified according to type of tumor (nonglial vs glial and diffuse pontine). * Regimen C (patients with glial tumors): * Stem cell harvesting (bone marrow and/or peripheral blood): Patients undergo leukapheresis or bone marrow aspiration to collect bone marrow or peripheral blood stem cells prior to beginning induction chemotherapy or after the first course of induction chemotherapy. * Induction chemotherapy: Patients receive vincristine IV on days 1, 8, and 15 of courses 1-3, oral temozolomide once daily on days 1-5, and carboplatin IV over 4 hours on days 1 and 2. Patients also receive G-CSF SC beginning on day 6 and continuing until blood counts recover. Treatment repeats every 28 days for 4 courses in the absence of disease progression or unacceptable toxicity. Patients with unresectable bulky disease and corticosteroid dependence are removed from study. All other patients proceed to consolidation chemotherapy. * Consolidation chemotherapy: Patients receive carboplatin IV over 4 hours on days -8 to -6 and thiotepa IV over 3 hours on days -5 to -3. * Autologous bone marrow or peripheral blood stem cell transplantation: Patients undergo reinfusion of bone marrow or peripheral blood stem cells on day 0. Patients also receive G-CSF SC beginning on day 1 and continuing until blood counts recover. * Radiotherapy: Beginning within 6 weeks after stem cell transplantation, patients \> 6 years of age at diagnosis undergo radiotherapy once daily 5 days a week for 4-6 weeks in the absence of disease progression or unacceptable toxicity. Patients ≤ 6 years of age undergo radiotherapy if there is evidence of tumor remaining after completion of induction chemotherapy. * Regimen D2 (patients with nonglial tumors): * Stem cell harvesting (bone marrow and/or peripheral blood): Patients undergo leukapheresis or bone marrow aspiration to collect bone marrow or peripheral blood stem cells prior to beginning induction chemotherapy or after the first course of induction chemotherapy. * Induction chemotherapy: * Courses 1, 3, and 5 (28 days per course): Patients receive cisplatin IV over 6 hours on day 1, cyclophosphamide IV over 1 hour and etoposide IV over 2 hours on days 2 and 3, high-dose methotrexate IV over 4 hours on day 4, and filgrastim (G-CSF) subcutaneously (SC) beginning on day 5 and continuing until blood counts recover. Patients also receive vincristine IV on days 1, 8, and 15 of courses 1 and 3. * Courses 2 and 4 (28 days per course): Patients receive oral temozolomide once daily on days 1-5, oral etoposide once daily on days 1-10, cyclophosphamide IV over 1 hour on days 11 and 12, and G-CSF SC beginning on day 13 and continuing until blood counts recover. Patients also receive vincristine IV on days 1, 8, and 15 of course 2. Patients with unresectable bulky disease and corticosteroid dependence are removed from study. All other patients proceed to consolidation chemotherapy. * Consolidation chemotherapy: Patients receive carboplatin IV over 4 hours on days -8 to -6 and thiotepa IV over 3 hours and etoposide IV over 3 hours on days -5 to -3. * Autologous bone marrow or peripheral blood stem cell transplantation: Patients undergo re-infusion of bone marrow or peripheral blood stem cells on day 0. Patients also receive G-CSF SC beginning on day 1 and continuing until blood counts recover. * Radiotherapy:Patients undergo radiotherapy as in regimen C. Patients in both regimens undergo neuropsychological testing after induction chemotherapy but before consolidation chemotherapy and then at 18, 36, and 54 months after completion of study treatment. Neuropsychometric and neuroendocrine testing is performed before and after radiotherapy. Quality of life is also assessed periodically. After completion of study treatment, patients are followed periodically. PROJECTED ACCRUAL: A total of 120 patients will be accrued for this study.