Correspondence to Dr Kristan J Aronson, Division of Cancer Care and Epidemiology, Cancer Research Institute, Queen’s University, Kingston, ON, K7L 3N6 , Canada; aronson{at}queensu.ca Objectives The ...

3 National Institute for Public Health and the Environment (RIVM), Bilthoven, Utrecht, The Netherlands 5 Public Health and Primary Care Directorate, Imperial College Healthcare NHS Trust, London, UK ...