[1] Oita Univ, Fac Med, Dept Gastroenterol & Pediat Surg, Oita 8795593, Japan
[2] Tokyo Med & Dent Univ, Dept Surg Oncol, Tokyo, Japan
[3] Kitasato Univ Hosp, Dept Surg, Sagamihara, Kanagawa, Japan
[4] Natl Canc Ctr, Div Colorectal Surg, Tokyo, Japan
[5] Natl Canc Ctr, Multiinst Clin Trial Support Ctr, JCOG Data Ctr, Tokyo 104, Japan
[6] Oita Univ, Fac Med, Oita 8795593, Japan