1. Gastrointestinal Cancer Center, Ordensklinikum Linz, Linz, Austria
2. Medical Faculty, Johannes Kepler University Linz, Linz, Austria
3. Department of Internal Medicine I, Wilhelminenspital, Vienna, Austria
4. Department of General and Visceral Surgery, Ordensklinikum Linz, Linz, Austria
5. Clinical Cancer Centre Upper Austria, Linz, Austria
6. Department of Internal Medicine IV, Hospital Wels-Grieskirchen, Wels, Austria