1. Department of Family Medicine and Chronic Care; Vrije Universiteit Brussel (VUB) and Ghent University; Brussels Belgium
2. Department of Medical Oncology; Ghent University Hospital; Ghent Belgium
3. Clinical and Descriptive Epidemiology Unit, Cancer Prevention and Research Institute; Florence Italy
4. Public Health Directorate, Regional Ministry of Health (Dirección General de Salud Pública, Consellería de Sanidad); Castile and Leon Valladolid Spain
5. Public Health Directorate, Regional Ministry of Health (Dirección General de Salud Pública, Conselleria de Sanitat); Comunitat Valenciana; Valencia Spain
6. Scientific Institute of Public Health (Wetenschappelijk Instituut Volksgezondheid, Institut Scientifique de Santé Publique); Unit of Health Services Research; Brussels Belgium