[1] Inst Canc Res, Sutton, Surrey, England
[2] Royal Marsden NHS Fdn Trust, Sutton, Surrey, England
[3] Addenbrookes Hosp, Dept Pathol & Mol Histopathol, Cambridge, England
[4] Univ Cambridge, Dept Pathol, Addenbrookes Hosp, Cambridge CB2 1QP, England
[5] MRC, Clin Trials Unit, London, England