Gastric cancer is the fourth most common malignancy and the third cause of cancer related-death worldwide. Although its incidence and mortality rates have progressively decreased in the last decades, the absolute number of cases is not going to decline in the next future. Gastric cancer remains an important public health problem. It affects about one-million people per year and it is associated with 800 000 deaths, with a higher incidence in males. Wide geographic variation in gastric cancer survival has been reported, depending mainly on differences in stages of diagnosis. This cancer is often detected at an advanced stage with an overall 5-years survival rate between 10% and 24%, as example in western populations including Europe. Gastric cancer is of multifactorial origin. The major risk factor associated to 80-90% of gastric cancer cases is Helicobacter pylori infection. In collaboration with J. Torres in Mexico, where the incidence of H. pylori infection and gastric cancer is high, we have previously identify mitochondrial DNA level in circulating leukocytes as a biomarker candidate for the detection of patients at risk of gastric cancer development (Fernandes et al, 2014). There is no appropriate screening strategies available for global application to reduce the global burden of gastric cancer. Thus, the characterization of biomarkers that would detect earliest the presence of gastric cancer lesions in absence of clinical symptoms is of public health interest. Such biomarkers will also be useful to monitor disease remission/progression during the treatment. They could also be an important tool to optimize anti-cancer therapeutic strategies. The aim of our project is to identify and to validate gastric cancer biomarker candidates in different populations with high incidence of gastric cancer and high mortality rate due to this cancer. These results will have an impact in clinic and can pave the way for the development of a non-invasive test for an early detection/diagnosis of patients with high risk of gastric cancer.