This study investigates the effects of dose-intensive tandem consolidation compared to a single cycle consolidation on event-free survival and overall survival in patients with certain central nervous system (CNS) tumors. CNS tumors can occur in the brain or spinal cord, and this study focuses on conditions like medulloblastoma and other embryonal tumors. The purpose is to see if the more intensive treatment can improve outcomes for these patients.

Participants in this study will undergo different treatment procedures depending on the study arm they are assigned to. One group will receive the dose-intensive tandem consolidation, while the other will receive a single cycle consolidation. The study will closely monitor patients to assess the effectiveness and safety of these treatments.

• Who can participate: Children under 10 years old with specific CNS tumors like medulloblastoma or CNS embryonal tumors can participate, provided they have not received prior chemotherapy or radiation, except for corticosteroids, and must start chemotherapy within a specific timeframe after surgery and imaging tests.
• Study details: Participants will be assigned to one of two study arms: dose-intensive tandem consolidation or single cycle consolidation, and the study will involve monitoring the safety and effectiveness of these treatments. A placebo is not used in this study.