1. Department of Gastroenterology, Hepatology and Clinical Oncology, Center of Postgraduate Medical Education, Warsaw, Poland
2. Department of Oncological Gastroenterology, The Maria Skłodowska-Curie National Research Institute of Oncology, Warsaw, Poland
3. Department of Radiotherapy, The Maria Skłodowska-Curie National Research Institute of Oncology, Warsaw, Poland
4. Department of Pathology and Laboratory Medicine, The Maria Skłodowska-Curie National Research Institute of Oncology, Warsaw, Poland