[1] Inst Gustave Roussy, Unite Gastroenterol, F-94805 Villejuif, France
[2] Univ Hosp Gasthuisberg, Louvain, Belgium
[3] Erasme Univ Hosp, B-1070 Brussels, Belgium
[4] Univ Ulm Klinikum, Ulm, Germany
[5] Marie Curie Sklodowska Mem Canc Ctr, Warsaw, Poland
[6] Inst Oncol, Warsaw, Poland
[7] Ambroise Pare Univ Hosp, Boulogne, France
[8] Univ Med Ctr, Nijmegen, Netherlands
[9] EORTC Data Ctr, Brussels, Belgium