1. Colorectal Unit, Department of Surgery, and Centre for Clinical Research Uppsala University, Västmanlands Hospital, Västerås, Sweden
2. Colorectal Unit, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
3. Division of Surgery, Department of Clinical Sciences, Danderyd Hospital, Karolinska Institute, Stockholm, Sweden
4. Department of Surgery, Vrinnevi Hospital, Norrköping, Sweden