[1] Vall dHebron Univ Hosp, Barcelona, Spain
[2] Inst Oncol, Barcelona, Spain
[3] Univ Hosp Gasthuisberg, Leuven, Belgium
[4] Katholieke Univ Leuven, Leuven, Belgium
[5] Seoul Natl Univ, Coll Med, Seoul, South Korea
[6] Yale Canc Ctr, New Haven, CT USA
[7] M Sklodowska Curie Mem Canc Ctr, Warsaw, Poland
[8] Seoul Natl Univ, Bundang Hosp, Coll Med, Seongnam, South Korea
[9] Riga East Univ Hosp, Riga, Latvia
[10] Pontificia Univ Catolica Chile, Santiago, Chile
[11] Yonsei Univ, Coll Med, Yonsei Canc Ctr, Seoul, South Korea
[12] Hosp Enfermedad Comun Igss Zona 9, Guatemala City, Guatemala
[13] Christie NHS, Manchester, Lancs, England
[14] Univ Sao Paulo, Inst Canc Estado Sao Paulo, Sao Paulo, Brazil
[15] Univ Canc Ctr Hamburg, Hamburg, Germany
[16] City Hope Comprehens Canc Ctr, Duarte, CA USA
[17] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles, CA 90095 USA
[18] Merck & Co Inc, Kenilworth, NJ USA
[19] Merck & Co Inc, Rahway, NJ 07065 USA
[20] Natl Canc Ctr Hosp East, Dept Gastrointestinal Oncol, Kashiwa, Chiba, Japan