1. U.Z. Antwerpen, Edegem, Belgium; Hospital Duran I Reynals-Institut Catala D’Oncologia, Barcelona, Spain; Hospital Universitario Marques de Valdecilla, Santander, Spain; Orszagos Onkologiai Intezet, Budapest, Hungary; Hospital 12 de Octubre, Madrid, Spain; Klinika Nowotworow Glowy i Szyi, Warsaw, Poland; U.Z. Gent, Gent, Belgium; Institute of Otolaringology AMS of Ukraine, Kiev, Ukraine; Szalbolcs-Szatmar Bereg Megyei Josa Andras Korhaz, Nyiregyhaza, Hungary; Merck KGaA, Darmstadt, Germany