Outcomes in comparison with those of historical cohorts of children aged ≥2 but <4 years with high-risk ALL undergoing HSCT. (A) Probability of OS over time and (B) probability of EFS over time, showing the ALL-SCT BFM International trial of TBI/Eto (blue; n = 16), the ALL-SCT BFM 2003 trial of TBI/Eto (red; n = 35), and children aged >2 but ≤4 years in the FORUM study of chemotherapeutic conditioning (green; n = 101).