Clare Gilham1, Emma J Crosbie2,3, Julian Peto4. 1. Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK clare.gilham@lshtm.ac.uk. 2. Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK. 3. Gynaecology Department, St Mary's Hospital, Manchester University NHS Foundation Trust, Manchester, UK. 4. Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.