1. Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands;
2. Department of Radiotherapy, Radboud University Medical Center, Nijmegen, The Netherlands;
3. Department of Medical Oncology, University Medical Center Utrecht, Utrecht, The Netherlands;
4. Julius center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands;
5. Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands;
6. Department of Radiotherapy, Leiden University Medical Center, Leiden, The Netherlands;
7. Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands