Mārcis Leja is 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 is a member of the European Cancer Mission Board and the Research Committee of the United European Gastroenterology. His special interest lies in the prevention and early detection of gastrointestinal cancer, particularly – gastric cancer. He is the principal investigator of the population-based gastric cancer prevention study GISTAR. The other areas of interest are related to the role of microbiome in cancer, and the use of volatile organic marker (VOC) diagnostic concept in gastrointestinal cancer detection as well as for other conditions.