1. Department of Oncological Gastroenterology, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
2. Department of Gastroenterology, Hepatology and Clinical Oncology, Centre of Postgraduate Medical Education, Warsaw, Poland
3. Clinical Effectiveness Research Group, Institute of Health and Society, University of Oslo, Norway
4. Department of Surgical Oncology, Medical University of Gdansk, Poland