Charlotte E Coles1, Judith M Bliss2, Philip M Poortmans3. 1. Department of Oncology, University of Cambridge, Cambridge CB2 0QQ, UK. Electronic address: colesc@doctors.org.uk. 2. Clinical Trials and Statistics Unit, The Institute of Cancer Research, London, UK. 3. Department of Radiation Oncology, Institut Curie, Paris, France; Université Paris Sciences et Lettres, Paris, France.