Department of Internal Medicine II, Medical Oncology, Comprehensive Cancer Center Mainfranken Würzburg, University Hospital Würzburg, Würzburg, Germany. Electronic address: kunzmann_v@ukw.de. Department of Medical Oncology and Division of Solid Tumour Translational Oncology, West German Cancer Center, University Medicine Essen, Essen, Germany. Comprehensive Cancer Center Munich, Klinikum rechts der Isar, Department of Internal Medicine II, Technical University Munich, Munich, Germany. North-German Trial Center for Innovative Oncology, Hematology-Oncology Practice Eppendorf, Hamburg, Germany. Department of Internal Medicine 5, Hematology and Medical Oncology, Paracelsus Medical University, Nürnberg, Germany. Department of Internal Medicine III, SLK-Clinics Heilbronn, Heilbronn, Germany. Department of Gastroenterology and Hepatology, University Hospital Cologne, Cologne, Germany. Division of Oncology and Hematology, Charite Campus Mitte and Charite Campus Virchow Klinikum, Freie Universität Berlin, Humboldt Universität zu Berlin, Berlin Institute of Health, Berlin Germany. Clinic for Gastroenterology, Hepatology and Gastrointestinal-Oncology, München Klinik Bogenhausen, Munich, Germany. Department of Internal Medicine I, Kliniken Nordoberpfalz, Klinikum Weiden, Weiden, Germany. Department of Medical Oncology and Comprehensive Cancer Center, Ludwig Maximilians University - Grosshadern, Munich, Germany. Department of Internal Medicine I, Ulm University Hospital, Ulm, Germany. Department of Biometrics, ClinAssess, Leverkusen, Germany. Clinical Research, Arbeitsgemeinschaft für Internistische Onkologie Studien, Berlin, Germany. Department of Surgery I, Comprehensive Cancer Center Mainfranken Würzburg, University Hospital Würzburg, Würzburg, Germany. Department of Surgery, Paracelsus Medical University, Nürnberg, Germany. Department of Surgery, School of Medicine, Technical University Munich, Munich, Germany. Department of Surgery, Charite Campus Mitte and Charite Campus Virchow Klinikum, Freie Universität Berlin, Humboldt Universität zu Berlin, Berlin Institute of Health, Berlin Germany. Department of Internal Medicine C, Gastroenterology and Gastrointestinal Oncology, Klinikum Ludwigshafen, Ludwigshafen, Germany. Department of Internal Medicine II, Medical Oncology, Comprehensive Cancer Center Mainfranken Würzburg, University Hospital Würzburg, Würzburg, Germany.