1. Gloucestershire Royal Hospital, Gloucester, United Kingdom
2. Institut Arnault Tzanck, Saint Laurent du Var, France
3. Imperial College London, London, United Kingdom
4. Cancer Registry of Norway and the Department of Gastroenterology, Oslo University Hospital, Oslo, Norway
5. CPO Piemonte and S. Giovanni University Hospital, Turin. Italy
6. Cancer Registry of Norway, Oslo, Norway
7. Erasmus MC University Medical Center, Rotterdam, the Netherlands
8. Central Research Institute of Ambulatory Health Care, Berlin, Germany
9. Screening Group, Early Detection and Prevention Section, International Agency for Research on Cancer, Lyon, France
10. Gastroenterology Unit, Valduce Hospital, Como, Italy