Author information: (1)Department of Gastroenterological Surgery II, Faculty of Medicine, Hokkaido University, N-15 W-7, Kita-Ku, Sapporo, Hokkaido, 060-8638, Japan. torunakamura@med.hokudai.ac.jp. (2)Center for Gastroenterology, Teine Keijinkai Hospital, 12-1-40 Maeda 1 Jo, Teine-ku, Sapporo, Hokkaido, 006-0811, Japan. (3)Department of Medical Oncology, School of Medicine, Sapporo Medical University, S1 W17, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan. (4)Department of Surgery, Surgical Oncology and Science, School of Medicine, Sapporo Medical University, S1 W17, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan. (5)Department of Gastroenterology and Hepatology, Faculty of Medicine, Hokkaido University, N-15 W-7, Kita-Ku, Sapporo, 060-8638, Japan. (6)Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, 1-1-1 Midorigaoka Higashi 2 Jo, Asahikawa, Hokkaido, 078-8510, Japan. (7)Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, S1 W17, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan. (8)Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, 1-1-1 Midorigaoka Higashi 2 Jo, Asahikawa, Hokkaido, 078-8510, Japan. (9)Department of Diagnostic and Interventional Radiology, Hokkaido University, N-15 W-7, Kita-Ku, Sapporo, 060-8638, Japan. (10)Department of Surgery, Hokkaido Gastroenterology Hospital, 1-2-10 Honcho 1 Jo, Higashi-ku, Sapporo, Hokkaido, 065-0041, Japan. (11)Department of Surgery, Kushiro Red Cross Hospital, 21-14 Shineicho, Kushiro, Hokkaido, 085-8512, Japan. (12)Department of Surgery, Obihiro Kosei General Hospital, 10-1 Nishi 14 Jominami, Obihiro, Hokkaido, 080-0024, Japan. (13)Department of Gastroenterology, Muroran City General Hospital, 3-8-1 Yamatecho, Muroran, Hokkaido, 051-8512, Japan. (14)Department of Gastroenterology, Steel Memorial Muroran Hospital, 1-45 Chiribetsucho, Muroran, Hokkaido, 050-0076, Japan. (15)Department of Gastroenterology, NTT East Sapporo Hospital, S1 W15 Chuo-ku, Sapporo, Hokkaido, 060-0061, Japan. (16)Department of Surgery, Asahikawa Red Cross Hospital, 1-1-1 Akebono 1 Jo, Asahikawa, Hokkaido, 070-8530, Japan. (17)Biostatistics Division, Hokkaido University Hospital Clinical Research and Medical Innovation Center, Kita 14, Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-8648, Japan. (18)Department of Gastroenterological Surgery II, Faculty of Medicine, Hokkaido University, N-15 W-7, Kita-Ku, Sapporo, Hokkaido, 060-8638, Japan.