[1] Univ Bonn, Dept Med & Gastroenterol, Gemeinschaftskrankenhaus Bonn, Acad Teaching Hosp, Bonner Talweg 4-6, D-53113 Bonn, Germany
[2] Inst Pathol Bonn Duisdorf, Bonn, Germany
[3] Saku Cent Hosp, Adv Care Ctr, Dept Endoscopy, Saku, Nagano, Japan
[4] Univ Bonn, Dept Gen & Abdominal Surg, Gemeinschaftskrankenhaus Bonn, Acad Teaching Hosp, Bonn, Germany
[5] Keio Univ, Sch Med, Canc Ctr, Div Res & Dev Minimally Invas Treatment, Tokyo, Japan