1. University Cancer Center Regensburg, University Hospital Regensburg, Regensburg, Germany
2. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Regensburg, Regensburg, Germany
3. Department of Radiation Oncology, University Hospital Regensburg, Regensburg, Germany
4. Center for Clinical Studies, University Hospital Regensburg, Regensburg, Germany