1. Department of Pediatric Oncology and Hematology, Jagiellonian University Medical College, 30-663 Krakow, Poland
2. Department of Pediatric Oncology and Hematology, University Children’s Hospital of Krakow, 30-663 Krakow, Poland
3. Department of Pediatric Bone Marrow Transplantation, Oncology and Hematology, Wroclaw Medical University, 50-367 Wroclaw, Poland
4. Department of Oncology, Children Memorial Health Institute, 04-730 Warsaw, Poland