1. Department of Paediatric Oncology; Institut Gustave Roussy; Villejuif France
2. Department of Cytopathology; Institut Gustave Roussy; Villejuif France
3. Department of Pathology; CHU Toulouse; Hôpital Purpan; Toulouse France
4. INSERM U563; Centre de Physiopathologie de Toulouse Purpan; Toulouse France
5. Biostatistics and Epidemiology Unit; Institut Gustave Roussy; Villejuif France
6. Univ Paris-Sud; Le Kremlin-Bicêtre France