Identification of circulating tumor cells as a promising method of genitourinary cancer diagnosis

Circulating tumor cells (CTCs) are cells circulating in the blood, which in terms of antigenic or genetic profile correspond to a particular type of cancer. It is suspected that CTCs possess properties of cancer stem cells. Detection, quantification and characterization of CTCs in the peripheral blood can be of great importance for modern oncology. In the case of early-stage disease, CTCs may help in cancer detection, estimation of metastasis risk and treatment prognosis. In advanced cancer patients, CTCs may also have prognostic significance and may facilitate monitoring response to treatment. Identification of CTCs in the circulation and their differentiation from hematopoietic cells and normal epithelial cells could be based on physical and biological properties such as size, density and expression of specific proteins. Immunomagnetic techniques are the most commonly used methods of CTCs isolation. CellSearch System (CSS) is the only test for detecting CTCs in the peripheral blood approved by the Food and Drug Administration (FDA) for clinical use. The paper presents the characteristics of circulating tumor cell isolation methods and the results of studies concerning CTCs isolation in patients with prostate, bladder and kidney cancer.