1. Department of Epidemiology; School of Medicine in Katowice Medical University of Silesia; Katowice Poland
2. The Department of Bone Marrow Transplantation and Onco-Hematology; Maria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology Gliwice Branch; Gliwice Poland
3. Department of Conventional and Intraoperative Radiotherapy; Maria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology Gliwice Branch; Gliwice Poland
4. Department of Biostatistics; Maria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology Gliwice Branch; Gliwice Poland