1. Department of Radiotherapy and Oncology, University of Frankfurt, Frankfurt, Germany
2. German Cancer Research Center, German Cancer Consortium, Frankfurt, Germany
3. Frankfurt Cancer Institute, Frankfurt, Germany
4. Department of Haematology and Oncology, Barmherzige Brüder Hospital, Regensburg, Germany
5. Department of Radiation Oncology, University of Würzburg, Würzburg, Germany
6. Department of Radiation Therapy, Poliklinik Chemnitz GmbH, Chemnitz, Germany
7. Department of Radiation Oncology and Radiotherapy, DiaCura & Klinikum Coburg, Coburg, Germany
8. Department of Radiation Therapy, University of Erlangen-Nürnberg, Erlangen, Germany
9. Department of Radiation Therapy, University of Leipzig, Leipzig, Germany
10. Department of General and Visceral Surgery, Klinikum Esslingen, Germany
11. Department of Radiation Therapy, University of Magdeburg, Magdeburg, Germany
12. Department of Radiation Oncology, Medical Center University of Freiburg, Faculty of Medicine, Freiburg, Germany
13. German Cancer Research Center, German Cancer Consortium, Freiburg, Germany
14. Praxis of Haematology and Oncology, Dresden, Germany
15. Department of Radiotherapy, Barmherzige Brüder Hospital Regensburg, Regensburg, Germany
16. Department of General and Visceral Surgery, University of Würzburg, Würzburg, Germany
17. Department of General and Visceral Surgery, University of Erlangen-Nürnberg, Erlangen, Germany
18. Department of Radiotherapy and Oncology, University of Rostock, Rostock, Germany
19. Department of General and Visceral Surgery, Klinikum Frankfurt Höchst, Germany
20. Department of General and Visceral Surgery, University of Frankfurt, Frankfurt, Germany
21. X-act Cologne Clinical Research GmbH, Cologne, Germany
22. Department of Medical Statistics, University Medical Center Göttingen, Göttingen, Germany
23. Department of General and Visceral Surgery, University Medical Center Göttingen, Göttingen, Germany
24. Department of Medical Oncology, University Hospital Mannheim, Mannheim, Germany
25. for the German Rectal Cancer Study Group