DISEASE CHARACTERISTICS: - Patients must be newly diagnosed with localized primary CNS nongerminomatous germ cell tumor (NGGCT) (Stratum 1) or localized primary CNS germinoma (Stratum 2); germ cell tumors (GCTs) located in the suprasellar, pineal, bifocal (pineal + suprasellar), and ventricles are eligible; tumors present in the above mentioned locations and with unifocal parenchymal extension are eligible - Stratum 1( NGGCT): Patients must have one of the following criteria: - Patients with serum and/or CSF hCGβ > 100 mIU/mL or any elevation of serum and CSF alpha-fetoprotein (AFP) > 10 ng/mL or greater than the institutional normal are eligible, irrespective of biopsy results - Patients with any of the following elements on biopsy/resection are eligible, irrespective of serum and/or CSF hCGβ and AFP levels: endodermal sinus tumor (yolk sac), embryonal carcinoma, choriocarcinoma, malignant/immature teratoma, and mixed GCT with malignant GCT elements - Stratum 2 (Germinoma): Patients must have one of the following criteria: - Patients with institutional normal AFP AND hCGβ 5 to ≤ 50 mIU/mL in serum and/or CSF are eligible; no histologic confirmation required - Patients with bifocal (pineal + suprasellar) involvement or pineal lesion with diabetes insipidus AND hCGβ ≤ 100 mIU/mL and institutional normal AFP in serum and/or CSF are eligible; no histologic confirmation required - Patients with histologically confirmed germinoma or germinoma mixed with mature teratoma and hCGβ ≤ 100 mIU/mL and institutional normal AFP in serum and/or CSF are eligible - Patients must have negative lumbar CSF cytology; lumbar CSF must be obtained unless medically contraindicated - Patients must be enrolled on ALTE07C1 prior to enrollment on ACNS1123 - Patients with mature teratoma with normal tumor markers are not eligible - Patients with tumors located outside the ventricles (basal ganglia, thalamus) are not eligible - Patients with metastatic disease by either MRI evaluation or lumbar CSF cytology are not eligible PATIENT CHARACTERISTICS: - Peripheral absolute neutrophil count (ANC) ≥ 1,000/μL - Platelet count ≥ 100,000/μL (transfusion independent) - Hemoglobin ≥ 8.0 g/dL (may receive red blood cell [RBC] transfusions) - Creatinine clearance or radioisotope GFR ≥ 70 mL/min/1.73 m² OR serum creatinine based on age/gender as follows: - 0.4 mg/dL ( 1 month to < 6 months of age) - 0.5 mg/dL (6 months to < 1 year of age) - 0.6 mg/dL (1 to < 2 years of age) - 0.8 mg/dL (2 to < 6 years of age) - 1.0 mg/dL (6 to < 10 years of age) - 1.2 mg/dL (10 to < 13 years of age) - 1.5 mg/dL (male) and 1.4 mg/dL (female) (13 to < 16 years of age) - 1.7 mg/dL (male) and 1.4 mg/dL (female) (≥ 16 years of age) - Total bilirubin ≤ 1.5 times upper limit of normal (ULN) - Serum glutamic oxaloacetic transaminase (SGOT) (aspartate aminotransferase [AST]) or serum glutamic pyruvate transaminase (SGPT) (alanine aminotransferase [ALT]) < 2.5 times ULN - Patients with seizure disorder may be enrolled if well controlled - Patients must not be in status, coma, or assisted ventilation prior to study enrollment - Female patients who are pregnant are ineligible - Lactating females are not eligible unless they have agreed not to breastfeed their infants - Female patients of childbearing potential are not eligible unless a negative pregnancy test result has been obtained - Sexually active patients of reproductive potential are not eligible unless they have agreed to use an effective contraceptive method for the duration of their study participation PRIOR CONCURRENT THERAPY: - Patients who had more than 1 prior surgery/biopsy are eligible - Patients must not have received any prior tumor-directed therapy other than surgical intervention and corticosteroids