1. Department of Otorhinolaryngology-Head and Neck Surgery; Albert-Ludwigs University; Freiburg Germany
2. Department of Otolaryngology-Head and Neck Surgery; VU University Medical Center; Amsterdam The Netherlands
3. Department of Nephrology and General Medicine; Albert-Ludwigs University; Freiburg Germany
4. Laboratory for Pathology; PAL Dordrecht; Dordrecht The Netherlands
5. Department of Otolaryngology; Hospital Universitario Central de Asturias; Oviedo Spain
6. Instituto Universitario de Oncología del Principado de Asturias; Oviedo Spain
7. Department of Otolaryngology-Head and Neck Surgery; Radboud University Nijmegen Medical Center; Nijmegen The Netherlands
8. Department of Otolaryngology-Head and Neck Surgery; Guthrie Health System; Sayre Pennsylvania
9. ENT Clinic; University of Udine; Italy