[1] Univ Bristol, Sch Social & Community Med, Surg Res Ctr, Bristol BS8 2PS, Avon, England
[2] Univ Hosp Bristol NHS Fdn Trust, Div Surg Head & Neck, Bristol BS2 8HW, Avon, England
[3] Velindre NHS Trust, Unit 2, Cardiff CF14 2TL, S Glam, Wales
[4] Univ Hosp Bristol NHS Fdn Trust, Bristol Haematol & Oncol Ctr, Bristol BS8 2PS, Avon, England
[5] Royal United Hosp, Bath BA1 3NG, Avon, England
[6] Royal Victoria Infirm, Northern Oesophagogastr Unit, Newcastle Upon Tyne NE1 4LP, Tyne & Wear, England