[1] Univ Hosp Portsmouth NHS Trust, Queen Alexandra Hosp, Dept Gen Surg, Portsmouth, England
[2] Univ Southampton, Fac Med, Sch Canc Sci, Southampton, England
[3] Guys & St Thomas Hosp NHS Fdn Trust, Dept Surg, London, England
[4] Imperial Coll London, Div Surg, London, England
[5] Univ Portsmouth, Dept Pharmacol & Biosci, Portsmouth, England
[6] Portsmouth Univ Hosp NHS Trust, Queen Alexandra Hosp, Dept Gen Surg, Portsmouth PO6 3LY, England