CIRCULATING TUMOR CELLS: CLINICAL SIGNIFICANCE IN BREAST CANCER (REVIEW)

Abstract

Circulating tumor cells (CTCs) constitute a heterogeneous population. Some tumor cells are cancer stem cells (CSCs), while others are in the process of the epithelial-mesenchymal transition (EMT); however, most CTCs are neither stem cells nor participants in the EMT. There is increasing interest in the study of the molecular biological characteristics of CTCs. Many researchers consider circulating tumor cells (CTC) as one of the variants of «liquid biopsy in real time». In this review, we discuss the clinical significance of CTCs in breast cancer and in particular the prognostic and predictive significance both in early stage and metastatic breast cancer, as well as the pathogenetic role of CTCs in venous thromboembolism. Evaluation of various characteristics of CTCs is promising for the study of new biomarkers and targets for targeted therapies. The clinical importance involves the determination of the heterogeneity of the CТC and in particular of the stem subpopulation of these cells, cells with signs of EMТ, with no evidence of stem cells, and with a combination of these features.