This study investigates how well reduced doses of radiation therapy and chemotherapy work in treating patients with a type of brain tumor called WNT-driven medulloblastoma. Medulloblastoma is a cancerous brain tumor that starts in the lower back part of the brain and can spread to other areas. The study aims to find out how effective this treatment is in preventing the tumor from growing or spreading in children aged 3 years and older.

Participants in the study will receive a lower dose of radiation therapy to the brain and spine, specifically 18 Gray (Gy) with an additional boost of 36 Gy to the tumor area, making a total of 54 Gy. The chemotherapy given will also be reduced, with no vincristine used during radiation therapy and a lower dose during maintenance treatment. These procedures are designed to see if they can effectively manage the disease while minimizing side effects.

• Who can participate: Children 3 years and older with newly diagnosed WNT-driven medulloblastoma can participate. Key eligibility includes a confirmed diagnosis, negative cerebrospinal fluid cytology, and no previous treatments except surgery and corticosteroids.
• Study details: Participants will undergo reduced radiation therapy and chemotherapy. Radiation will be given in lower doses to the brain and spine, and chemotherapy will be reduced, excluding vincristine during radiation. A placebo will not be used in this study.