1. Pediatric Oncology Department Hippokration General Hospital Thessaloniki Greece
2. Hellenic Society for Social Pediatrics and Health Promotion Athens Greece
3. Department of Hygiene and Epidemiology University of Ioannina School of Medicine Ioannina Greece
4. Center for Evidence Synthesis in Health, Department of Health Services, Policy and Practice, School of Public Health Brown University Providence Rhode Island
5. Department of Epidemiology, Hygiene and Medical Statistics National and Kapodistrian University of Athens Athens Greece