1. Department of Pediatric Hematology and Oncology; University Hospital Muenster; Muenster Germany
2. Department of Pediatric Oncology, Emma Children's Hospital; Academic Medical Centre; Amsterdam The Netherlands
3. Department of Maxillofacial Surgery; University Hospital Muenster; Muenster Germany
4. St Anna Children's Hospital; Vienna Austria
5. Children's Cancer Research Institute; Vienna Austria