[1] Ruhr Univ Bochum, Marien Hosp Herne, Dept Radiat Oncol, D-44625 Herne, Germany
[2] Ruhr Univ Bochum, St Josef Hosp Bochum, D-44625 Herne, Germany
[3] Tech Univ Munich, Klinikum Rechts Isar, Dept Radiat Oncol, D-80290 Munich, Germany
[4] Univ Clin Leipzig, Univ Canc Ctr Leipzig, Leipzig, Germany
[5] Tech Univ Munich, Dept Internal Med Hematol Oncol 3, D-80290 Munich, Germany
[6] Tech Univ Munich, Klinikum Rechts Isar, Dept Surg, D-80290 Munich, Germany
[7] Tech Univ Munich, Klinikum Rechts Isar, Inst Med Stat & Epidemiol, D-80290 Munich, Germany
[8] Univ Hosp Split, Ctr Oncol & Radiotherapy, Split, Croatia
[9] Nordland Hosp Trust, Dept Oncol & Palliat Med, Bodo, Norway
[10] Univ Tromso, Fac Hlth Sci, Inst Clin Med, Tromso, Norway
[11] Krankenhaus Barmherzigen Schwestern Linz, Dept Radiat Oncol, Linz, Austria
[12] Ruhr Univ Bochum, Univ Klinikum, Marienhosp Herne, Klin Strahlentherapie & Radioonkol, Herne, Germany