affiliation not provided to SSRN, Leiden University - Department of Radiation Oncology, Spaarne Gasthuis - Spaarne Gasthuis Hospital, affiliation not provided to SSRN, Leiden University, Medical Center (LUMC), Department of Pathology, Leiden University Medical Centre - Department of Obstetrics and Gynaecology, University of Copenhagen - Rigshospitalet, University of Copenhagen - Copenhagen University Hospital, University of Copenhagen - Copenhagen University Hospital, Erasmus University Medical Center Rotterdam - Department of Radiation Oncology, Leiden University - Department of Radiation Oncology, Leiden University, Medical Center (LUMC), Department of Pathology and University of Copenhagen - Rigshospitalet