1. Department of Otorhinolaryngology–Head and Neck Surgery, University Hospital of Marburg, University of Giessen, Marburg, Germany
2. Department of Otorhinolaryngology–Head and Neck Surgery, University Hospital of Mannheim, University of Heidelberg, Mannheim, Germany
3. Department of Medical Statistics and Biomathematics, University of Heidelberg, Mannheim, Germany
4. Department of Pathology, University Hospital of Mannheim, University of Heidelberg, Mannheim, Germany