1. Department of Otorhinolaryngology-Head and Neck Surgery, University of Helsinki, Helsinki University Hospital, Helsinki, Finland;
2. Department of Otorhinolaryngology-Head and Neck Surgery, Tampere University Hospital, University of Tampere, Tampere, Finland;
3. Department of Otorhinolaryngology-Head and Neck Surgery, Turku University Hospital, University of Turku, Turku, Finland;
4. Department of Oncology, Helsinki University Hospital, University of Helsinki, Helsinki, Finland;
5. Department of Otorhinolaryngology-Head and Neck Surgery, Oulu University Hospital, University of Oulu, Oulu, Finland;
6. Department of Otorhinolaryngology-Head and Neck Surgery, Kuopio University Hospital, University of Eastern Finland, Kuopio, Finland;
7. Department of Pathology, University of Helsinki, HUSLAB, Helsinki University Hospital, Helsinki, Finland;
8. Research Programs Unit, Translational Cancer Biology, University of Helsinki, Helsinki, Finland;
9. Department of Surgery, University of Helsinki, Helsinki University Hospital, Helsinki, Finland;
10. Department of Oncology, Turku University Hospital, University of Turku, Turku, Finland;
11. Department of Pathology, Oulu University Hospital, University of Oulu, Oulu, Finland;
12. Department of Pathology, Turku University Hospital, University of Turku, Turku, Finland