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

DISEASE CHARACTERISTICS:

* Histologically confirmed malignant brain tumor, including any of the following:

  * Posterior fossa medulloblastoma/primitive neuroectodermal tumor (PNET)\*

    * All stages allowed
    * Must be \< 4 years of age at diagnosis unless there is evidence of postoperative residual tumor (\> 1.5 cm² tumor area) or evidence of neuraxis or extraneural dissemination (high-stage)
    * Medulloblastoma, cerebral neuroblastoma, and ependymoblastoma allowed

      * Low-stage (standard-risk) medulloblastoma not allowed in patients \> 4 years of age
  * Ependymoma\*

    * All stages and locations allowed
    * Cellular and anaplastic subtypes allowed (no myxopapillary ependymomas of the spinal cord)
    * Must be \< 36 months of age at diagnosis for posterior fossa tumor OR \< 72 months of age for supratentorial tumor
    * Evidence of neuraxis dissemination irrespective of primary site
    * No cellular (low-grade) supratentorial ependymomas at any age with complete resection of parenchymally based (i.e., not periventricular) supratentorial tumors
  * Brain stem tumor\*

    * All stages allowed irrespective of extent of resection
    * No unbiopsied diffuse intrinsic pontine tumor
    * Tumor pathologically confirmed to be either malignant glioma or PNET allowed
  * High-grade glioma\*\*
  * Primary atypical teratoid/rhabdoid tumor of the CNS\*
  * Choroid plexus carcinoma or atypical choroid plexus papilloma\*

    * All stages and locations allowed
  * Anaplastic astrocytoma\*\*
  * Glioblastoma multiforme\*\*
  * Anaplastic oligodendroglioma\*\*
  * Anaplastic ganglioglioma\*\*
  * Other anaplastic mixed gliomas\*\*
  * Small-cell glioblastoma\*\*
  * Giant-cell glioblastoma\*\*
  * Gliosarcoma\*\*
* The following diagnoses or subtypes are not allowed:

  * Choroid plexus papilloma
  * Pineocytoma
  * Low-grade mixed glioma
  * Primary CNS germ cell tumor
  * Primary CNS lymphoma
  * Solid leukemic lesions (i.e., chloromas, granulocytic sarcomas)
  * Pleomorphic xanthoastrocytoma, low grade
  * Desmoplastic ganglioglioma
  * Low-grade astrocytoma
* Previously untreated disease
* Has undergone definitive surgery within the past 42 days NOTE: \*Patients receive treatment according to regimen D2

NOTE: \*\*Patients receive treatment according to regimen C

PATIENT CHARACTERISTICS:

* Bilirubin \< 1.5 mg/dL
* ALT and AST \< 2.5 times upper limit of normal
* Creatinine clearance and/or glomerular filtration rate ≥ 60 mL/min

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* No prior radiotherapy or chemotherapy
* Prior corticosteroids allowed
* No concurrent corticosteroids for antiemesis only
* No concurrent brachytherapy or electron radiotherapy
* No concurrent dairy products or grapefruit juice with temozolomide administration