1. Department of Radiation Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Poland
2. Department of Laryngology, Silesian Medical University, Katowice, Poland
3. Radiotherapy Clinic and Teaching Hospital, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Poland
4. Department of Pathology, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Poland
5. Department of Chemotherapy, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Poland