title: Select biomarkers for tumors of the gastrointestinal tract: present and future.
abstract: BACKGROUND
  Advances in molecular biomarkers of the gastrointestinal tract have contributed to a decline in the incidence of and mortality from diseases of the gastrointestinal tract. The discovery and clinical validation of new biomarkers are important to personalized cancer therapy, and numerous clinical trials are currently ongoing to help identify individualized therapy affecting these biomarkers and molecular mechanisms they represent. Distinct molecular pathways leading to cancers of the colorectum, esophagus, stomach, small bowel, and pancreas have been identified. Using biomarkers in these pathways to direct patient care, including selection of proper molecular testing for identification of actionable mutations and reporting the results of these biomarkers to guide clinicians and genetic counselors, is paramount.
  
  
  OBJECTIVE
  To examine and review select clinically actionable biomarkers of the colon, esophagus, stomach, small bowel, and pancreas, including present and future biomarkers with relevant clinical trials.
  
  
  METHODS
  Extensive literature review and practical and consultation experience of the authors.
  
  
  CONCLUSIONS
  Although numerous biomarkers have been identified and are currently guiding patient therapy, few have shown evidence of clinical utility in the management of patients with gastrointestinal cancers. Inconsistent results and discordant proposed algorithms for testing were identified throughout the literature; however, the potential for biomarkers to improve outcomes for patients with gastrointestinal cancer remains high. Continued advances through high-quality studies are needed.
authors.affiliation: From Molecular Diagnostics, Department of Pathology, St. Joseph Mercy Hospital, Ypsilanti, Michigan (Dr Bartley); and the Division of Pathology and Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas (Dr Hamilton).
authors.forename: Angela N
authors.initials: AN
authors.lastname: Bartley
authors.forename: Stanley R
authors.initials: SR
authors.lastname: Hamilton
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D005544:Forecasting; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000628:therapy; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods / Q000639:trends; D006801:Humans; D009154:Mutation; D057285:Precision Medicine / Q000379:methods / Q000639:trends; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor