1. Pediatric Oncology, Hospital Nacional de Ninos Benjamin Bloom, San Salvador, El Salvador
2. Division of Haematology/Oncology and Program in Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada
3. Division of Hematology/Oncology, Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
4. Department of Pediatrics, University of Milano‐Bicocca, Monza, Italy
5. Pediatric Oncology, St. Jude Children's Research Hospital, Memphis, TN