With the use of risk-adapted chemotherapy based treatments, outcomes for children and adolescents with hematological malignancies have significantly improved in industrialized countries. For example, in acute lymphoblastic leukemia (ALL), the most common pediatric cancer, with a peak incidence in preschool-children, long-term survival steadily improved in US Children’s Oncology Group (COG) clinical trials; 499 patients treated from 1970–1972 had a survival rate at 10 years of ∼20% versus >90% in 11,806 patients treated from 2010–2015. 1 Similar or better results have been achieved in major single-institution clinical trials including the Total Therapy protocols at St. Jude Children’s Research Hospital (SJCRH).