[1] Hokkaido Univ Hosp, Dept Gastroenterol & Hepatol, Sapporo, Hokkaido, Japan
[2] Shizuoka Canc Ctr, Div Gastrointestinal Oncol, Nagaizumi, Shizuoka, Japan
[3] Aichi Canc Ctr Hosp, Dept Clin Oncol, Nagoya, Aichi, Japan
[4] Hokkaido Univ Hosp, Canc Ctr, Sapporo, Hokkaido, Japan
[5] Yokohama City Univ, Sch Med, Dept Biostat, Yokohama, Kanagawa, Japan