1. Department of Otorhinolaryngology/Head and Neck Surgery University Medical Center Groningen University of Groningen Groningen The Netherlands
2. Department of Anesthesiology University Medical Center Groningen University of Groningen Groningen The Netherlands
3. Department of Otorhinolaryngology Amsterdam UMC University of Amsterdam Amsterdam The Netherlands
4. Department of Research Netherlands Comprehensive Cancer Organization (IKNL) Utrecht The Netherlands
5. Department of Epidemiology University Medical Center Groningen University of Groningen Groningen The Netherlands