1. Department of Surgery, Sundsvall Hospital, Umeå University, Umeå, Sweden;
2. Department of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden;
3. Department of Surgical Sciences, Uppsala Academic Hospital, Uppsala University, Uppsala, Sweden;
4. Regional Cancer Center, Uppsala, Sweden;
5. Department of Oncology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden;
6. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden