Iridium Netwerk, University of Turin, Humanitas University, University of Brescia, University Hospital Careggi, University Hospital Zurich, Radboud University Nijmegen - Radboud University Medical Center, affiliation not provided to SSRN, University of Ljubljana, Ghent University Hospital - Department of Radiation Oncology, University of Milan, University of Antwerp, AZ Groeninge, Università Campus Bio-Medico di Roma, Catharina Hospital, Hospital de la Santa Creu i Sant Pau, affiliation not provided to SSRN, affiliation not provided to SSRN, Deventer Ziekenhuis - Deventer Hospital, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, European Organisation for Research and Treatment of Cancer (EORTC), affiliation not provided to SSRN, University Hospital Zurich - Department of Radiation Oncology and Iridium Netwerk