A narrative review of diagnostic and therapeutic potential of isolation ofcirculating tumor cells

Abstract

Background. The spread of metastasis (metastasizing) is the leading cause of cancerrelated death, and the ability of tumor cells to migrate through surrounding tissue and to intravasate into blood or lymphatic vessels is an important interim step in the transition from localized to systemic disease. In 5% to 10% of all cases of advanced cancer, metastatic lesions are detected before the primary tumor. The cellular basis of metastasis is the ability of tumor cells to leave the primary focus and to enter systemic circulation, i.e., the so-called circulating tumor cells. Early detection of these cells is of high diagnostic value and may serve as a specific prognostic marker of treatment effectiveness. Therefore, it is a rationale for review and analysis of state-of-the-art information on approaches to quantitative and qualitative analysis of circulating tumor cells. Aim – to characterize current diagnostic and therapeutic potential of isolation of circulating tumor cells. Materials and methods. Literature search was performed with the following keywords: circulating tumor cells, metastases, migration and invasion, technologies of circulating tumor cells isolation, receptor-ligand interactions of circulating tumor cells. On the second stage, article abstracts were screened and non-relevant publications were excluded. On the third stage, full-text articles were assessed for meeting the inclusion criteria for the list of references and for the relevance of studies. Results and discussion. As compared with conventional biopsy, the study of circulating tumor cells is a relatively inexpensive and non-invasive method, so it can be repeated many times during therapy, which makes this technique a powerful tool for monitoring the development of cancer. Given the low number of circulating tumor cells in whole peripheral blood, their isolation is a decisive step for further analysis. Monitoring the content of circulating tumor cells during therapy is a tool that allows you to evaluate the development of the disease in real time, even before the appearance of obvious clinical signs of relapse. A decrease in the number of circulating tumor cells after surgery and/or chemotherapy is likely to be a sign of remission. In contrast, an increase in the number of circulating tumor cells indicates a reactivation of the disease, which should lead to a re-examination of therapy. Conclusions. Early detection and characterization of circulating tumor cells is a new strategy for predicting and identifying the recurrence of cancer pathology. Circulating tumor cells detected before and after adjuvant therapy, radiotherapy, or surgical resection of the primary tumor have been described as independent risk factors for tumor recurrence and death.