1 CRUK-MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK; NIHR University College London Hospitals Biomedical Research Centre, UCL Cancer Institute, London WC1E 6DD, UK. Electronic address: ricky.sharma@oncology.ox.ac.uk.
2 Western Hospital, Footscray, VIC, Australia.
3 Division of Radiation Oncology, Penn State Hershey Cancer Centre and School of Medicine, PA, USA.
4 Department of Radiology and Nuclear Medicine, University of Magdeburg, Magdeburg, Germany.
5 Department of Hepatogastroenterology and GI Oncology, Université Paris Descartes, Paris, France.
6 Centre for Statistics in Medicine, University of Oxford, Oxford, UK.
7 University of Western Australia, Perth, WA, Australia.