1. Pediatric Hematology Oncology Division, Department of Pediatrics, Vrije University Medical Center, Vrije University, Amsterdam, the Netherlands
2. Pediatric Hematology Oncology Division, Department of Pediatrics, Dr Sardjito Hospital, Gadjah Mada University, Yogyakarta, Indonesia
3. Department of Psycho-Social Research and Epidemiology, Dutch Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, Netherlands