1. Department of Gastroenterological Oncology, The Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Warsaw, Poland
2. Department of Gastroenterology, Hepatology and Clinical Oncology, Medical Center for Postgraduate Education, Warsaw, Poland
3. Department of Cancer Prevention, The Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Warsaw, Poland
4. Department of Health Management and Health Economics, University of Oslo, Oslo, Norway
5. Department of Research and Development, Telemark Hospital, Skien, Norway
6. Department of Gastroenterology, Telemark Hospital, Skien, Norway