A Study of Lower Radiotherapy Dose to Treat Children With CNS Germinoma

Inclusion Criteria: * Patients must be ≥ 3 years and \< 30 years at the time of study enrollment * Patients must be newly-diagnosed primary localized germinoma of the suprasellar and/or pineal region by pathology and/or serum and/or CSF hCGbeta 5-50 mIU/mL AND institutional normal AFP (or ≤ 10 ng/mL if no institutional normal exists), including tumors with contiguous ventricular or unifocal parenchymal extension. No histologic confirmation required * Patients with EITHER (A) bifocal (pineal + suprasellar) involvement OR (B) pineal lesion with diabetes insipidus (DI) AND hCGbeta ≤ 100 mIU/mL in serum and/or CSF AND institutional normal AFP (or ≤ 10 ng/mL if no institutional normal exists) in both serum and CSF. No histologic confirmation required * Patients with hCGbeta 51-100 mIU/mL in serum and/or CSF and institutional normal AFP (or ≤ 10 ng/mL if no institutional normal exists) in both serum and CSF. Histologic confirmation of germinoma IS required * Patients with germinoma of the basal ganglia and or/thalamic primary sites are eligible * Patients with metastatic germinoma including non-contiguous disease or distant disease in the brain, ventricles, or spine are eligible * Patients with germinoma admixed with mature teratoma are eligible * Patients must have a performance status corresponding to Eastern Cooperative Oncology Group (ECOG) scores of 0, 1 or 2. Use Karnofsky for patients \> 16 years of age and Lansky for patients ≤ 16 years of age * Patients must have eligibil…