[1] Fdn IRCCS, Ist Nazl Tumori, Evaluat Epidemiol Unit, Milan, Italy
[2] Italian Natl Inst Hlth, Natl Ctr Epidemiol, Rome, Italy
[3] Dept Hlth, Epidemiol Unit, Girona, Spain
[4] Dept Hlth, Girona Canc Registry, Girona, Spain
[5] Catalan Inst Oncol, Girona, Spain
[6] Childhood Canc Registry Piedmont, Turin, Italy
[7] Univ Valencia, Spanish Natl Registry Childhood Tumours, Valencia, Spain
[8] Univ Oxford, Childhood Canc Res Grp, Oxford OX1 2JD, England