1. The Polyposis Registry, St. Mark’s Hospital, London, United Kingdom
2. Department of Surgery and Cancer, Imperial College London, United Kingdom
3. Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Netherlands
4. Department of Surgery, Basildon and Thurrock University Hospital, Basildon, United Kingdom
5. Department of Surgery, University College Hospital, London, United Kingdom