J D Martin-Smith1, S P Mackey2, K W Ramsey3. 1. The Royal Marsden NHS Foundation Trust, Fulham Road, London SW3 6JJ, United Kingdom. 2. Queen Victoria Hospital NHS Foundation Trust, Holtye Road, East Grinstead, West Sussex RH19 3DZ, United Kingdom. 3. The Royal Marsden NHS Foundation Trust, Fulham Road, London SW3 6JJ, United Kingdom. Electronic address: jmartins@tcd.ie.