1. Department of Otorhinolaryngology, Head and Neck Surgery University Medical Center Groningen, University of Groningen Groningen The Netherlands
2. Department of Epidemiology University Medical Center Groningen, University of Groningen Groningen The Netherlands
3. Department of Oral and Maxillofacial Surgery University Medical Center Groningen, University of Groningen Groningen The Netherlands
4. Department of Otorhinolaryngology, Head and Neck Surgery Haaglanden Medical Center The Hague The Netherlands
5. Department of Radiation Oncology University Medical Center Groningen, University of Groningen Groningen The Netherlands
6. Department of Research Netherlands Comprehensive Cancer Organisation (IKNL) Utrecht The Netherlands