ABSTRACT
In the area of biomedical research, a biomarker is generally dened as a distinctive biological or biologically derived indicator of a health condition. Hence, a biomarker can be a substance found in the blood, urine, or other body ·uid, an imaging technique, a hormone, or a gene or protein whose change in expression levels indicates the development or presence of a disease. For many diseases, predictive biomarkers are well known. For example, prostate-specic antigen (PSA) is used to diagnose prostate cancer, hemoglobin A1c (HbA1c) for diabetes, cholesterol for coronary and vascular disease, C-reactive protein (CRP) for in·ammation, and estrogen receptors for breast cancer, to name a few.
