The goal of this observational study is to quantify the burden of particularly severe, long-term adverse effects in childhood acute lymphoblastic leukemia (ALL) survivors. The adverse effects include 21 severe health conditions recently selected and defined as Severe Toxicities by an international collaboration of ALL consortia. The main questions the study aims to answer for childhood ALL patients are: * What is the chance of surviving without any Severe Toxicities during the first 5 years after ALL diagnosis? * What is the average cumulative burden of different Severe Toxicities during the first 5 years after ALL diagnosis? The study uses standard-care follow-up data for childhood ALL patients from an international collaboration of five ALL consortia from Europe, the US, and Australia.