Treatment of Patients With Newly Diagnosed Medulloblastoma, Supratentorial Primitive Neuroectodermal Tumor, or Atypical Teratoid Rhabdoid Tumor

Drugs used in chemotherapy, such as vincristine, cisplatin, and cyclophosphamide, work in different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage tumor cells. Combining radiation therapy with chemotherapy may kill more tumor cells. Autologous stem cell transplant may be able to replace blood-forming cells that were destroyed by chemotherapy or radiation therapy. It is not yet known which radiation therapy regimen combined with chemotherapy and donor stem cell transplant is more effective in treating medulloblastoma, supratentorial primitive neuroectodermal tumor, or atypical teratoid rhabdoid tumor. This phase III trial is studying two different regimens of radiation therapy when given together with chemotherapy and autologous stem cell transplant to see how well they work in treating patients with newly diagnosed medulloblastoma, supratentorial primitive neuroectodermal tumor, or atypical teratoid rhabdoid tumor. PRIMARY OBJECTIVE: * To assess the relationship between ERBB2 protein expression in tumors and progression-free survival probability for patients with medulloblastoma. * To estimate the frequency of mutations associated with SHH and WNT tumors (as defined by gene expression profiling) via targeted sequencing performed in an independent cohort of WNT and SHH tumors (also defined by gene expression profiling).