His main clinical and research interests are on peptic ulcer diseases, clinical and laboratory research on gastric tumours, endoscopy and minimally invasive surgery for the upper gastrointestinal tract, and surgical education. He introduced to Queen Mary Hospital laparoscopic upper gastrointestinal surgery in 1995, laparoscopic gastrectomy in 2001, and bariatric surgery in 2007. He pioneered the use of intracorporeal hand-sewn suture anastomosis after laparoscopic gastrectomy.
He is the President (2021 – now), Honorary Advisor (2017 – now), and Secretary General (2005 – 2011) of the Asian Surgical Association. He is the President (2018 – 2022), and Council Member (2006 – now) of the Hong Kong Society of Upper Gastrointestinal Surgeons. He is the Founding President (2015 – 2021), and Council Member (2015 – now) of the Hong Kong Endoscopic Ultrasonography Society. He is the President (2019 – now) of the International Society for Digestive Surgery – Asian Pacific. He was a member (2016 – 2018) of the International Relations Committee of the Society for Surgery of the Alimentary Tract (SSAT), USA. He is a member (2020 – now) of the Program Subcommittee, Stomach/Bariatric/Metabolic, of the Society for Surgery of the Alimentary Tract (SSAT), USA. He is a member (2021 – now) of the Board of Directors, and Treasurer (2021 – now), of the Asian Pacific Digestive Week Federation (APDWF).