1. Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark;
2. Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA;
3. Department of Otorhinolaryngology, Head & Neck Surgery and Audiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark;
4. Division of Biostatistics and Bioinformatics, University of Maryland Greenebaum Cancer Center and Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA