1 Clinical Trials Unit, Pediatric Hematology-Oncology Department, Children's University Hospital Niño Jesús, Av. Menendez Pelayo 65, 28009, Madrid, Spain.
2 Statistics Department, European Organisation for Research and Treatment of Cancer (EORTC) Headquarters, Av. E. Mounier 83/11, 1200, Brussels, Belgium.
3 Pediatric OncoGenomics Unit, Pediatric Hematology-Oncology, Children's University Hospital Niño Jesús, Av. Menendez Pelayo 65, 28009, Madrid, Spain. Electronic address: [email protected].