Emma Sverdén1,2, Sheraz R Markar1,3, Lars Agreus4,5, Jesper Lagergren1,6. 1. Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. 2. Department of Upper Gastrointestinal Surgery, South Hospital, Stockholm, Sweden. 3. Department of Surgery and Cancer, Imperial College, London, UK. 4. Division of Family Medicine and Primary Care, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. 5. University of Newcastle, Australia. 6. School of Cancer and Pharmaceutical Sciences, King's College London, and Guy's and St Thomas' NHS Foundation Trust, UK.