Abstract
Confirming the diagnosis of cancer has largely been the role of the pathologist, through examination and evaluation of tumor tissue. An adjunct to this process is the identification of a tumor marker, which can be found in tumor tissue or released from a tumor into the blood or other body fluids. The blood level of a tumor marker may indicate that a certain type of cancer is in the body. The use of tumor markers is increasing in the care of patients with colorectal cancer (CRC). One of the most commonly used tumor markers to monitor patients with stages II and III CRC for recurrence is carcinoembryonic antigen (CEA); however, the use of CEA has significant limitations. Biomarkers are biologic molecules found in the blood, other body fluids, or tissues that can represent a normal or abnormal process of a condition or disease. In CRC, KRAS has been the most notable biomarker advance, in terms of its predictive value for treatment with epidermal growth factor receptor inhibitors. The BRAF gene has more recently gained attention as a prognostic biomarker, although its predictive value for response to treatment is inconclusive. The recent upsurge of biomarkers in identifying disease prognosis, predictive response to treatment, or likelihood of treatment toxicities has contributed additional perspectives to the CRC disease management landscape.
