Mārcis Leja is a Professor of Medicine, Director of the Institute of Clinical and Preventive Medicine, University of Latvia, Head of the Dept. of Research, Riga East University hospital, and a consulting gastroenterologist at the Digestive Diseases Centre. He has served as a member of the European Cancer Mission Board from 2019 to 2021 and is a member of Research Committee member of the United European Gastroenterology (UEG) as well as the European Helicobacter and Microbiota Study Group (EHMSG). His special interest lies in the prevention and early detection of gastrointestinal cancer. He is the principal investigator of the population-based gastric cancer prevention study GISTAR (www.gistar.eu). The other areas of research interest are related to the use of volatile organic marker (VOC) diagnostic concept in gastrointestinal cancer detection as well as for other conditions, the role of microbiota in health and disease as well as the use of large data for prevention and early detection.