1. Department of Otorhinolaryngology-Head and Neck Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
2. Department of Oncology, Oslo University Hospital, Oslo, Norway
3. Department of Oncology, St. Olavs Hospital, Trondheim, Norway
4. Department of Otorhinolaryngology-Head and Neck Surgery, Landspitali University Hospital, Reykjavik, Iceland
5. Department of Hematology, Oncology, and Radiation Physics, Skåne University Hospital, Lund, Sweden
6. Department of Otorhinolaryngology-Head and Neck Surgery, Karolinska University Hospital, Stockholm, Sweden
7. Department of Oncology, Tampere University Hospital, Tampere, Finland
8. Department of Otorhinolaryngology – Head and Neck Surgery, Odense University Hospital, Odense, Denmark
9. Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
10. Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark