1. Department of Radiotherapy and Oncology, University of Frankfurt, Frankfurt, Germany
2. Frankfurt Cancer Institute, Frankfurt, Germany
3. Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston
4. Department of Medical Oncology, University Hospital Mannheim, University Heidelberg, Heidelberg, Germany
5. Department of General, Visceral, and Pediatric Surgery, University Medical Center, Göttingen, Germany
6. German Cancer Research Center, Heidelberg, German Cancer Consortium, Partner Site Frankfurt am Main, Frankfurt, Germany