[1] Tokyo Med Univ, Dept Gastroenterol & Hepatol, Shinjyuku Ku, Tokyo 1600023, Japan
[2] Teine Keijinkai Hosp, Ctr Gastroenterol, Sapporo, Hokkaido, Japan
[3] Japan Red Cross Date Gen Hosp, Dept Gastroenterol, Date, Japan
[4] Toda Chuo Gen Hosp, Dept Gastroenterol, Toda, Saitama, Japan
[5] Teikyo Univ Hosp, Dept Surg, Tokyo, Japan
[6] Asahikawa City Hosp, Dept Gastroenterol, Asahikawa, Hokkaido, Japan