[1] Yokohama City Univ, Med Ctr, Gastroenterol Ctr, Yokohama, Kanagawa, Japan
[2] Ofuna Chuo Hosp, Radiat Oncolocy Ctr, Kamakura, Kanagawa, Japan
[3] Yokohama City Univ, Grad Sch Med, Dept Biostat, Yokohama, Kanagawa, Japan
[4] Yokohama City Univ, Grad Sch Med, Dept Gastroenterol, Yokohama, Kanagawa, Japan