1. Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine; University of Athens; Athens Greece
2. National Cancer Registry of Ukraine; National Institute of Cancer; Kiev Ukraine
3. Childhood Cancer Sub-registry of Belarus; Belarusian Research Center for Pediatric Oncology, Hematology and Immunology; Minsk Belarus
4. Bulgarian National Cancer Registry; National Oncology Hospital; Sofia Bulgaria
5. Institute of Public Health of Serbia; Belgrade Serbia
6. Izmir Cancer Registry, Izmir Hub; Izmir & Hacettepe University Institute of Public Health; Izmir Turkey
7. North Region Cancer Registry of Portugal (RORENO); Portuguese Oncology Institute of Porto; Porto Portugal
8. Croatian National Cancer Registry; Croatian National Institute of Public Health; Zagreb Croatia
9. Cancer Registry of Republic of Slovenia; Institute of Oncology; Ljubljana Slovenia
10. Central Region Cancer Registry of Portugal (ROR-Centro); Portuguese Oncology Institute of Coimbra; Coimbra Portugal
11. Cyprus Cancer Registry-Health Monitoring Unit; Ministry of Health; Nicosia Cyprus
12. Department of Health Information and Research; Malta National Cancer Registry; Pieta Malta
13. Regional Cancer Registry of Iasi; National Institute of Public Health; Iasi Romania
14. Regional Cancer Registry of Cluj; Oncological Institute “Ion Chiricuta”; Cluj-Napoca Romania
15. Oncology Department; “Mitera” Children's Hospital; Athens Greece
16. Second Department of Pediatrics; Aristotelian University of Thessaloniki, AHEPA General Hospital; Thessaloniki Greece
17. Department of Pediatric Hematology and Oncology; Hippokration Hospital; Thessaloniki Greece
18. Haematology-Oncology Unit, First Department of Pediatrics; Athens University Medical School, “Aghia Sophia” Children's Hospital; Athens Greece
19. Department of Pediatric Haematology-Oncology; “Aghia Sophia” Children's Hospital; Athens Greece
20. Department of Pediatric Hematology-Oncology; University of Crete, University Hospital of Heraklion; Heraklion Greece
21. Department of Pediatric Hematology-Oncology; “Pan. & Agl. Kyriakou” Children's Hospital; Athens Greece