1. Departments of Pathology and Medical Biology University Medical Center Groningen; University of Groningen; Groningen The Netherlands
2. Otorhinolaryngology and Head and Neck Surgery, University Medical Center Groningen, University of Groningen; Groningen The Netherlands
3. Epidemiology, University Medical Center Groningen, University of Groningen; Groningen The Netherlands
4. Radiation Oncology, University Medical Center Groningen, University of Groningen; Groningen The Netherlands
5. Martini Hospital; Groningen The Netherlands