Medulloblastoma, WNT-activated

This clinical study is going to be done on a type of brain tumor in children called Medulloblastoma. The WNT pathway type of medulloblastoma is considered to be low risk and have the best outcomes in terms of survival. With the current standard of care for this type of medulloblastoma it is believed by the investigators that we are over treating the disease and increasing the long term side effects of these children. Several groups in the world are testing de-intensification of treatment in this favourable subset of children who experience long term late side effects of therapy. By reducing the dose to the craniospinal axis and keeping the total tumor bed dose the same in this study the investigators are expecting to reduce some of the late side effects of craniospinal irradiation without compromising disease control and survival.