Curative treatments for medulloblastoma impart significant toxicity on the developing brain. Though changes to white matter have been described, there remains a limited understanding of the effects of treatment on the structural connectome, which is thought to subserve complex and dynamic behaviors. Identifying compromise within the connectome may elucidate mechanisms of toxicity among survivors. We analyzed connectomic differences between survivors and age-matched controls. We identified two networks situated posteriorly with reduced white matter microstructure in survivors. Our findings complement studies showing long-term effects of treatment on brain structure, and localize these effects to areas around the site of the tumor.