[1] London Sch Hyg & Trop Med, Dept Noncommunicable Dis Epidemiol, London WC1, England
[2] Canc Prevent Inst Calif, Fremont, CA 94538 USA
[3] St Jude Childrens Res Hosp, Dept Oncol, Leukemia & Lymphoma Div, Memphis, TN 38105 USA
[4] Lucile Packard Childrens Hosp, Dept Pediat Hematol Oncol, Stanford, CA USA
[5] London Sch Hyg & Trop Med, Dept Med Stat, London WC1, England
[6] Inst Biomed Res Girona, Epidemiol Unity, Girona, Spain
[7] Inst Biomed Res Girona, Canc Registry Girona, Girona, Spain
[8] Dept Hlth Res & Policy, Div Epidemiol, Stanford, CA USA