Tumor Biomarkers: Clinical Utility, Promises and Problems

The word biomarker has different meanings to different physicians. A biomarker is defined as “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention” by the National Institutes of Health Biomarkers Definitions Working Group held in 1998. Thus, the definition of a biomarker may include routinely measured parameters in clinical practice such as blood pressure and pulse or it could indicate a substances used in the diagnosis, treatment and monitoring of a disease. Here, we discuss tumor biomarkers as an example of commonly used clinical biomarkers that impact patient diagnosis and prognosis. In addition, a review of the limitations of common biomarkers and a highlight of emerging and promising biomarkers are presented in the manuscript.