Molecular Signatures and Precision Medicine of Gastric Cancer

Gastric cancer (GC) is the fifth most commonly diagnosed cancer worldwide and the second leading cause of cancer-related deaths. Adenocarcinoma accounts for approximately 95% of all malignant gastric neoplasms. Most localized GC (stages II and III) are best treated with multimodality therapy with a 5-year survival in approximately 40% of patients; however, advanced GC only has limited treatment options with poor prognosis. GC is a highly heterogenous disease. Historically, many classification systems have been proposed, including anatomical classification (Borrmann classification, Siewert and Stein classification), histological classification (WHO classification, Lauren’s classification), and extent of disease (early gastric cancer vs. advanced cancer). Originally proposed in 1965, the Lauren’s classification divides GC into intestinal- and diffuse-types that are quite distinct in the histological features, epidemiology, and etiology.