1. a Ste-Justine Hospital, University of Montreal, Montreal, Canada
2. b Children's Cancer Research Institute, Vienna, Austria
3. c University Children's Hospital Basel, Basel, Switzerland
4. d Huntsman Cancer Institute & Primary Children's Medical Center, University of Utah, Salt Lake City, Utah, USA
5. e Department of Radiotherapy, University Hospital Muenster, Münster, Germany
6. f Department of Pathology, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
7. g University of Muenster, Children's Hospital, Paediatric Haematology and Oncology, Muenster, Germany