1. Department of Head and Neck Surgery; Greek Anticancer Institute; Saint Savvas Hospital; Athens Greece
2. Center for Rehabilitation & Department of Oral and Maxillofacial Surgery; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
3. Department of Oral and Maxillofacial Surgery; Section of Oncology; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
4. Department of Otolaryngology; Hospital Universitario Central de Asturias; Oviedo Spain
5. Instituto Universitario de Oncología del Principado de Asturias; Oviedo Spain
6. University of Udine School of Medicine; Udine Italy
7. Department of Radiation Oncology; Institute of Oncology; Ljubljana Slovenia
8. Department of Otolaryngology-Head and Neck Surgery; Radboud University Medical Center; Nijmegen The Netherlands