Proton Beam Radiation Therapy for Central Nervous System (CNS) Germ Cell Tumors

Inclusion Criteria: * Histologically confirmed germ cell tumor or elevated AFP or B-HCG in the setting of radiographic disease consistent with a germ cell tumor. Disease must be confined to the central nervous system. * Participants do not need to have measurable disease. Most patients will not have measurable disease at the time of treatment. * 3 years of age or older and 25 years of age or younger at the time of diagnosis because this study evaluates this disease entity in the pediatric population which may differ from the adult population. * Life expectancy of greater than 12 months. * ECOG performance status of 0, 1 or 2 * Baseline MRI of the brain and spinal axis with gadolinium and prior to any chemotherapy is required. If surgical resection is performed a post-operative MRI is required. If the patient receives chemotherapy prior to radiation, a post-chemotherapy MRI of the brain is required. If spinal involvement was seen on initial MRI and prior to chemotherapy, a MRI of the spine is required after chemotherapy and prior to radiation. * Serum and lumbar CSF must be obtained to evaluate for alpha fetoprotein (AFP) and beta human chorionic gonadotropin (HCG). This is needed to stratify patients into pure GCT and NGGCT. * Women of child-bearing potential and men must agree to use adequate contraception prior to study entry and for the duration of study participation. Exclusion Criteria: * Patients will be ineligible if any prior therapeutic radiation therapy \> 200 cGy has been delivered to the central nervous system. * Patients will be ineligible if chemotherapy was completed greater than 1 year from the planned start date of radiation therapy or if the patient is referred for radiation therapy after a relapse following a regimen with chemotherapy alone. * Individuals with a history of a different malignancy are ineligible except for the following circumstances: Disease-free for at least 5 years and are deemed by the investigator to be at low risk for recurrence of that malignancy. Individuals diagnosed and treated within the past 5 years for cervical cancer in situ and basal cell or squamous cell carcinoma of the skin. * Pregnant females