[1] Ruhr Univ Bochum, Marien Hosp Herne, Dept Radiat Oncol, Holkeskampring 40, D-44625 Herne, Germany
[2] Nordland Hosp Bodo, Dept Oncol & Palliat Med, Bodo, Norway
[3] Univ Tromso, Fac Hlth Sci, Dept Clin Med, N-9001 Tromso, Norway
[4] Ruhr Univ Bochum, Marien Hosp Herne, Dept Surg, Herne, Germany
[5] Ruhr Univ Bochum, Sankt Josef Hosp Bochum, Dept Radiat Oncol, Univ Str 150, Bochum, Germany
[6] Univ Witten Herdecke, Acad Hosp, Ev Krankenhaus Witten, Dept Radiat Oncol, Witten, Germany