1 Medical Research Council Clinical Trials Unit at University College London, Institute of Clinical Trials & Methodology, University College London, London WC1V 6LJ, UK. Electronic address: [email protected].
2 Department of Surgery and Cancer, Imperial College London, London, UK.
3 Medical Research Council Clinical Trials Unit at University College London, Institute of Clinical Trials & Methodology, University College London, London WC1V 6LJ, UK.
4 Department of Medical Oncology, The Christie National Health Service Foundation Trust and University of Manchester, Manchester, UK.