1 Department of Gastroenterological Oncology, The Maria Sklodowska-Curie Institute Oncology Center, Warsaw, Poland; Department of Gastroenterology, Hepatology and Oncology, Medical Center for Postgraduate Education, Warsaw, Poland.
2 Department of Gastroenterological Oncology, The Maria Sklodowska-Curie Institute Oncology Center, Warsaw, Poland; Department of Cancer Prevention, The Maria Sklodowska-Curie Institute Oncology Center, Warsaw, Poland; Department of Gastroenterology, Hepatology and Oncology, Medical Center for Postgraduate Education, Warsaw, Poland; Institute of Health and Society, University of Oslo, Oslo, Norway.