1. Department of Abdominal Surgery, Universitair Ziekenhuis Gasthuisberg, Leuven, Belgium
2. Colorectal Surgery Unit, Cliniques Universitaires Saint-Luc, Brussels, Belgium
3. Department of Surgery, Erasme University Hospital, Brussels, Belgium
4. Department of Gastrointestinal Surgery, Ghent University Hospital, Ghent, Belgium
5. Unité de Chirurgie Digestive, Hôpital de Jolimont, Haine-Saint-Paul, Belgium
6. Belgian Cancer Registry, Brussels, Belgium
7. I-Biostat, Katholieke Universiteit Leuven, Leuven, and Universiteit Hasselt, Diepenbeek, Belgium