Biomarkers for gastric cancer and the related premalignant conditions

Although gastric cancer is declining in incidence when estimated in standardized ratio statistics, it will still remain an important health-care problem during the coming decades. Currently, most of cancer cases outside Japan are diagnosed at advanced stages when radical management is substantially less effective. Infection with Helicobacter pylori bacteria is related to the majority of cases. Atrophy, intestinal metaplasia, and dysplasia are well-characterized precursors of the cancer. Currently, the only method available to diagnose exactly these lesions is upper endoscopy with an appropriate biopsy work-up. Biomarkers for noninvasive detection of early gastric cancer and/or the precursors would be of substantial importance to decrease the cancer-related mortality, in particular in the developing part of the world. This chapter discusses the available gastric cancer screening programs and the potential existing methods, including modalities of endoscopy and tests for identification of the precursors (e.g., pepsinogen tests) as well as the limitations of these methods. The role of host genetic factors, including polymorphisms of proinflammatory cytokines, is addressed; the potential role of miRNAs and epigenetics is discussed. The rare entity of hereditary gastric cancer linked to CDH1 gene mutation as well as the host genetic factors being related to increased cancer risk is also discussed. Insight is given into the new developments in the field, including the detection of specific cancer autoantibodies and volatile organic components in the exhaled breath.