[1] Kushiro Rosai Hosp, Dept Med Oncol, Kushiro, Japan
[2] Hokkaido Univ Hosp, Div Canc Ctr, Sapporo, Hokkaido, Japan
[3] Hokkaido Univ Hosp, Dept Gastroenterol & Hepatol, Sapporo, Hokkaido, Japan
[4] Sapporo City Gen Hosp, Dept Gastroenterol, Sapporo, Hokkaido, Japan
[5] Japanese Red Cross Akita Hosp, Dept Med Oncol, Akita, Japan
[6] KKR Sapporo Med Ctr, Dept Med Oncol, Sapporo, Hokkaido, Japan
[7] Nakadori Gen Hosp, Dept Surg, Akita, Japan
[8] Teine Keijinkai Hosp, Dept Med Oncol, Sapporo, Hokkaido, Japan
[9] Hirosaki Univ, Grad Sch Med, Dept Med Oncol, Hirosaki, Aomori, Japan
[10] Tonan Hosp, Dept Med Oncol, Sapporo, Hokkaido, Japan
[11] Sapporo Med Ctr NTT EC, Dept Gastroenterol, Sapporo, Hokkaido, Japan
[12] Keiyukai Sapporo Hosp, Dept Med Oncol, Sapporo, Hokkaido, Japan
[13] Hokkaido Gastroenterol Hosp, Dept Internal Med, Sapporo, Hokkaido, Japan
[14] Hokkaido Gastrointestinal Canc Study Grp, Data Ctr, Sapporo, Hokkaido, Japan
[15] Misawa City Hosp, Misawa, Japan