[1] Univ Ioannina, Sch Med, Dept Hyg & Epidemiol, Clin & Mol Epidemiol Unit, GR-45110 Ioannina, Greece
[2] Royal Orthopaed Hosp, Birmingham B31 2AP, W Midlands, England
[3] Univ Florence, Dept Human Pathol & Oncol, Florence, Italy
[4] Hosp Univ La Fe, Dept Med Oncol, Valencia, Spain
[5] Hop Enfants Armand Trousseau, Serv Hematooncol Pediat, Paris, France
[6] Med Univ Vienna, Dept Orthopaed, Vienna, Austria
[7] Ankara Oncol Hosp, Dept Pediat Oncol, Ankara, Turkey
[8] Marmara Univ, Med Ctr, Dept Pediat Hematol Oncol, Istanbul, Turkey
[9] Univ Navarra, Dept Pediat, E-31080 Pamplona, Spain
[10] Univ Navarra, Dept Orthoped, E-31080 Pamplona, Spain
[11] Univ Navarra Clin, Pamplona, Spain
[12] GRAACC UNIFESP, Inst Oncol Pediat, Pediat Oncol Sect, Sao Paulo, Brazil
[13] Med Fac Zagreb, Inst Pathol, Zagreb, Croatia
[14] Cincinnati Childrens Hosp, Med Ctr, Cincinnati, OH USA
[15] Tufts Univ, Sch Med, Tufts Med Ctr, Inst Clin Res & Hlth Policy Studies,Dept Med, Boston, MA 02111 USA