1. Department of Otorhinolaryngology, Head & Neck Surgery, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, The Netherlands
2. Netherlands Comprehensive Cancer Organization (IKNL), Department of Research and Development, 3511 DT Utrecht, The Netherlands
3. Department of Epidemiology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, The Netherlands
4. Department of Pathology & Medical Biology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, The Netherlands