[1] Hokkaido Univ, Grad Sch Med, Dept Gastroenterol, Kita Ku, Sapporo, Hokkaido 0608648, Japan
[2] Hokkaido Univ Hosp, Ctr Canc, Sapporo, Hokkaido 060, Japan
[3] Keiyukai Sapporo Hosp, Dept Surg Oncol, Sapporo, Hokkaido, Japan
[4] Hakodate Municipal Hosp, Dept Gastroenterol, Hakodate, Hokkaido, Japan
[5] Sapporo City Gen Hosp, Dept Gastroenterol, Sapporo, Hokkaido, Japan
[6] Hokkaido Gastroenterol Hosp, Dept Internal Med, Sapporo, Hokkaido, Japan
[7] Kushiro Rosai Hosp, Dept Internal Med, Kushiro, Japan
[8] Toyama Univ, Dept Internal Med 3, Toyama 930, Japan
[9] Japanese Red Cross Kitami Hosp, Dept Gastroenterol, Kitami, Hokkaido, Japan
[10] Misawa City Hosp, Dept Med Oncol, Misawa, Japan