[1] Univ Oxford, Nuffield Dept Populat Hlth, Canc Epidemiol Unit, Oxford, England
[2] Univ Oxford, Nuffield Dept Populat Hlth, Oxford, England
[3] Univ Sheffield, Sheffield Ctr Hlth & Related Res, Sheffield, England
[4] Univ Oxford, Bodleian Hlth Care Lib, Oxford, England
[5] Univ Oxford, Nuffield Dept Populat Hlth, Canc Epidemiol Unit, Oxford, England
[6] Oxford Univ Hosp NHS Fdn Trust, Oxford, England