Oncomarker research

Markers of malignant growth include substances of various natures: antigens, hormones, enzymes, glycoproteins, lipids, proteins, metabolites. The synthesis of markers is determined by the peculiarities of cancer cell metabolism. Abnormal expression of the genome is one of the main mechanisms of marker production by tumor cells, which causes the synthesis of embryonic, placental and ectopic enzymes, antigens and hormones. A wide range of markers is known for various cancer localizations, but only a few can to some extent correspond to the concept of an "ideal marker".

The diagnostic value of a tumor marker depends on its sensitivity and specificity. There are no tumor markers yet that meet the definition of ideal, i.e. markers with almost 100% specificity (not detected in benign diseases and in healthy people) and 100% sensitivity (definitely detectable even at early stages of tumor development). When studying tumor markers, the concept of "cutoff" (cutoff point) is of great importance - the permissible upper limit of tumor marker concentration in healthy people and in patients with benign tumors. The cutoff point does not have a fixed value and can be changed in accordance with the purpose of the test. If the goal is to identify as many patients with tumors as possible, the cutoff point is set at a low level to increase sensitivity, at the cost of an inevitable increase in the frequency of false positive results (decrease in specificity). If it is necessary to increase the probability that a positive test result corresponds to the presence of a tumor, the cutoff point should be set at a high level to increase specificity at the expense of increasing the rate of false negative results (decreasing sensitivity).

For most tumor markers, standardized cutoff point values have been established, which are adhered to by the most authoritative researchers.

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