University Hospital Zurich, University Hospital Zurich, University of Freiburg, Leeds Teaching Hospitals NHS Trust, The University of Manchester, affiliation not provided to SSRN, University of Zurich, Karolinska Institutet - Karolinska University Hospital, affiliation not provided to SSRN, University of Oslo - Oslo University Hospital, Government of the United Kingdom, Department of Health, National Health Service (NHS), Mount Vernon Cancer Centre Northwood, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, affiliation not provided to SSRN, University of Leeds, affiliation not provided to SSRN, University Hospital Zurich - Department of Radiation Oncology and University Hospital Zurich