1. Department of Surgery, Helsinki University Central Hospital, Helsinki, Finland
2. Department of Oncology, Helsinki University Central Hospital, Helsinki, Finland
3. Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland
4. Department of Surgery, Tampere University Hospital, Tampere, Finland
5. Department of Surgery, Kuopio University Hospital, Kuopio, Finland
6. Department of Surgery, Oulu University Hospital, Oulu, Finland