1. Department of Surgical Oncology; Hokkaido University Graduate School of Medicine; Kita-15, Nishi-7, Kita-ku Sapporo 060-8638 Japan
2. Department of Surgical Pathology; Hokkaido University Hospital; Sapporo Japan
3. Department of Human Pathology; Kanazawa University Graduate School of Medicine; 13-1 Takaramachi Kanazawa 920-8640 Japan
4. Department of Gastroenterology; Hokkaido University Graduate School of Medicine; Kita-15, Nishi-7, Kita-ku Sapporo 060-8638 Japan