1. Department of Otorhinolaryngology/Head and Neck Surgery University of Groningen University Medical Center Groningen Groningen The Netherlands
2. Department of Radiation Oncology Radboud University Medical Center Nijmegen The Netherlands
3. University Center for Geriatric Medicine University Medical Center Groningen Groningen The Netherlands
4. Department of Surgical Oncology University Medical Center Groningen University of Groningen Groningen The Netherlands
5. Department of Epidemiology University Medical Center Groningen University of Groningen Groningen The Netherlands