ABSTRACT
Tumor markers (TMs) are substances that are often present in abnormally high concentrations in the blood, urine, or tissue of patients with certain types of cancer. They include proteins, hormones, enzymes, and other molecular species [8,23]. The measurement of the concentrations of TMs can be useful in the early detection of cancer, differentiating benign from malignant conditions, evaluating the extent of the disease, monitoring the response of the tumor to therapy, and predicting recurrence [21]. Most TMs have limited specicity, and so the measurement of a single TM is usually not sufcient to diagnose cancer. However, most cancers have more than one marker associated with their incidence, and in many cases the diagnostic value of TMs can be signicantly increased if panels of markers are measured [1,3,13,20,29]. In addition to tumor-specic markers, the inclusion of tumor-associated markers and growth-related TMs into screening panels may also be of benet. The presence of these substances and the order of their appearance may be of major signicance in cancer screening.
