1. Ninewells Hospital and Medical School, Dundee, United Kingdom
2. Knappschafts Hospital, Ruhr University of Bochum, Bochum, Germany
3. Erasmus MC University Medical Centre, Rotterdam, the Netherlands
4. Gastroenterology Unit, Valduce Hospital, Como, Italy
5. Screening Group, Early Detection and Prevention Section, International Agency for Research on Cancer, Lyon, France