1. Department of General and Visceral Surgery, Georg-August University, Göttingen, Germany
2. Department of Medical Statistics, Georg-August University, Göttingen, Germany
3. Department of Haematology and Oncology, University Medical Centre Göttingen, Georg-August University, Göttingen, Germany
4. University Cancer Centre Leipzig, University Clinic Leipzig, Leipzig, Germany
5. Institute of Pathology Nordhessen, Kassel, Germany