Background: The present state of knowledge of tumor development and progression mechanisms, and tumor cells’ sensitivity or resistance to various drugs and interventions allows transition from standard common schemes of therapy to so called “personalized medicine” - treatment choice according to patient’s individual characteristics and biological properties of the tumor. This task can be successfully solved with the help of tumor biological markers characterizing such malignant cell fundamental properties as invasion and metastasizing, unlimited proliferation, resistance to apoptosis, neoangiogenesis, etc. The main goal of this lecture is the assessment of the present state of tumor biological markers preclinical studies, established clinical implications, and prospects of modern high-throughput molecular biologic technologies introduction into routine clinical practice.

Materials and methods: Critical analysis of up-to-date publications and personal results in this field according to the international organizations (ETMG/ISOBM, ASKO) guidelines.

Main points: The longest and most successful history of biological markers’ clinical implication belongs to breast cancer. It started in 1970s with steroid receptor determination for evaluation of sensitivity to endocrine therapy, and now encloses at least 3 obligatory markers - estrogen and progesterone receptors, and HER2/neu (the target of Herceptin), not only for individual specific treatment choice, but also for construction of various prognostic indices including the so-called breast cancer molecular classification. Still under evaluation is the possibility of tumor-associated proteases (uPA) and their inhibitor (PAI-1) measurement in the tumor for early relapse risk assessment in node-negative patients. And for the same purpose two chip-based “gene signature” systems were proposed - MammaPrint™ (70 genes) and Oncotype DX (21 genes).

In certain cases the study of tumor DNA specific somatic mutation status is now recommended. Thus, NCLC therapy with low molecular weight epidermal growth factor receptor (EGFR) inhibitors requires preliminary EGFR mutations (first of all, L858R deletion) evaluation. And in colorectal cancer, treatment with anti-EGFR antibodies is recommended only when wild-type KRAS gene is found.

Another important group of clinically valuable biological markers comprise intracellular signaling proteins (PI3K/Akt, NFkB, mTOR, etc.) that affect tumor sensitivity to classical chemo-, hormone and radiotherapy, and can become targets for existing and new molecular-targeted preparations.

Conclusion: Due to achievements of biochemistry, molecular biology and biotechnology we have now a wide range of biologically important parameters that can help in prognosis and adequate treatment choice in various types of cancer at different disease stages, but many of them still require critical evaluation.