The examinations of tumor markers in serum and tissue, their accurate indications, timing and validity (specificity, sensitivity, positive and negative predictive value and the other parameters evaluated according to requirements of good laboratory practice) as well as their applications in terms of recommendations of International working groups for tumor markers (EGTM 1, 2) are summarized in the contemporary view of clinical oncology. Structural classification of tumor markers, individual indications of their examinations, biological half-time for individual tumor markers, and explanation of ROC (Receiver Operating Characteristics) curves are presented in individual tables. Also the perspective methods of molecular DNA genetics and epigenetic are mentioned.

        Key words: tumor markers, indications, timing, validity, epigenetics.