1. Department of Hematology and Oncology, University Department Internal Medicine-Oncology, Pius-Hospital, Medical Campus University of Oldenburg, Oldenburg, Germany
2. Department of Radiotherapy, University Hospital Essen, Essen, Germany
3. Department of Radiotherapy and Radiooncology, University Department of Medical Physics, Pius-Hospital Oldenburg, University of Oldenburg, Oldenburg, Germany
4. Department of Medical Oncology, West German Cancer Center, Ruhrlandklinik, University of Duisburg-Essen, Essen, Germany