1. Department of Surgical Oncology, Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore, Pakistan
2. Institute of Head and Neck Diseases, Evangelical Hospital, Vienna, Austria
3. Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
4. Department of Clinical Pathology, Medical University of Vienna, Vienna, Austria
5. Institute of Radio-Oncology, Kaiser-Franz-Josef Hospital, Vienna, Austria
6. Department of Otorhinolaryngology, Head and Neck Surgery, Rudolfstiftung Hospital, Vienna, Austria