Michalski JM, Janss AJ, Vezina LG, et al. - Since the prognosis of average-risk medulloblastoma has improved with multimodality therapy, however, adverse effects of radiation therapy on patient outcomes can be devastating, researchers sought to de-intensify the craniospinal irradiation (CSI) dose in younger children and reduce the volume of the boost in all children receiving treatment for this disease. The sample consisted of 549 patients, of which 464 were eligible and evaluable to compare posterior fossa radiation therapy vs involved field radiation therapy and 226 for standard-dose CSI vs low-dose CSI. According to this phase III trial, reduced radiation boost volume in average-risk MB is safe and does not jeopardize survival. Reducing CSI dose in young children with average-risk MB leads to worse outcomes, possibly in a subgroup-dependent manner, but is linked to better neurocognitive outcomes. Molecularly informed patient selection merits further investigation for children with MB who may be candidates for late-effect sparing approaches.