1 aDepartment of Cancer Epidemiology, University of Turin and CPO Piemonte, Turin bDepartment of Cancer Epidemiology, University of Eastern Piedmont and CPO Piemonte, Novara cSanti Antonio e Biagio e Cesare Arrigo Hospital, Alessandria, Italy dDepartment of Population Health Sciences and Education, St George's University of London, London, UK.