1. Department of Oncology, Herlev Hospital, Herlev, Denmark
2. Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark, on behalf of the Danish Head and Neck Cancer Group
3. Department of Oncology, Odense University Hospital, Odense, Denmark
4. Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
5. Department of Oncology, Aalborg University Hospital, Aalborg, Denmark