[1] Royal Coll Surgeons England, Clin Effectiveness Unit, London, England
[2] London Sch Hyg & Trop Med, Dept Hlth Serv Res & Policy, London, England
[3] Guys & St Thomas NHS Fdn Trust, Dept Oncol, London, England
[4] Cambridge Univ Hosp NHS Fdn Trust, Dept Colorectal Surg, Cambridge, England
[5] Christie NHS Fdn Trust, Dept Oncol, Manchester, England
[6] Univ Manchester, Sch Med Sci, Manchester, England
[7] Royal Coll Surgeons England, Clin Effectiveness Unit, 38-43 Lincolns Inn Fields, London WC2A 3PE, England