This is a prospective randomized clinical trial, to determine whether dose- intensive tandem Consolidation, in a randomized comparison with single cycle Consolidation, provides an event-free survival (EFS) and overall survival (OS). The study population will be high-risk patients (non-Wnt and non-Shh sub-groups) with medulloblastoma, and for all patients with central nervous system (CNS) embryonal tumors completing Head Start 4 Induction. This study will further determine whether the additional labor intensity (duration of hospitalizations and short-term and long-term morbidities) associated...