Patients

The study included all children aged between 1 and 17.9 years at diagnosis of B-cell precursor or T–cell ALL between 2008 and 2015. All patients were treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL2008 protocol, which has a prospective online registration system encompassing detailed data on patients’ characteristics, treatment, response to treatment, and toxicities (including any CNS toxicity, posterior reversible encephalopathy syndrome [PRES] and seizures).^14-16 Patients with CNS toxicities were identified in the NOPHO ALL2008 registry (Online Supplementary Methods).