1. Department of Otorhinolaryngology; Head and Neck Surgery; Helsinki University Central Hospital and University of Helsinki; Helsinki Finland
2. Department of Otorhinolaryngology; Head and Neck Surgery; Oulu University Hospital and University of Oulu; Oulu Finland
3. Department of Oncology; Helsinki University Central Hospital; Helsinki Finland
4. Department of Otorhinolaryngology; Head and Neck Surgery; Turku University Hospital and University of Turku; Turku Finlan
5. Department of Otorhinolaryngology; Head and Neck Surgery; Tampere University Hospital and University of Tampere; Tampere Finland
6. Department of Otorhinolaryngology; Head and Neck Surgery; Kuopio University Hospital and University of Kuopio; Kuopio Finland
7. Department of Oncology; Turku University Hospital and University of Turku; Turku Finland