The overall purpose of this study is threefold: first, this study aims to deepen the knowledge about particular patterns of long-term cognitive impairment in pediatric cancer survivors. Understanding the nature of cognitive deficits in this population will be helpful for developing tailored therapeutic strategies. Second, the availability of well-designed child-friendly evidence-based training is of major clinical relevance to prevent school problems and further decline of cognitive functions. Third, the detection of training-induced neuronal changes in white-matter structure will give insight into the functional plasticity of the child's brain. In addition, training-induced changes in white matter would build strong evidence for the effect of the particular intervention.