Personalized Approaches to Gastrointestinal Cancers: Importance of Integrating Genomic Information to Guide Therapy.

Cancers are characterized by complex tumor heterogeneity driven by subclones with differential genotypes and phenotypes, which then drives cancer behavior. As genomic strategies become feasible on smaller samples such as biopsies, coupled with decreasing costs of these approaches, clinicians will increasingly use genomic information to drive therapeutic decision making. Early applications of such personalized approaches are discussed. Genetic testing of high-risk family members may identify patients with germline mutations who can have prophylactic surgeries as a cancer prevention strategy. This article discusses examples of successful targeted therapy. Clinical trials need to incorporate genetic testing to stratify patients into different groups.