Recent Progress in Enhanced Cancer Diagnosis, Prognosis, and Monitoring Using a Combined Analysis of the Number of Circulating Tumor Cells (CTCs) and Other Clinical Parameters

Abstract

Analysis of circulating tumor cells (CTCs) holds promise to diagnose cancer or monitor its development. Among the methods, counting CTC numbers in blood samples could be the simplest way to implement it. Nevertheless, its clinical utility has not yet been fully accepted. The reasons could be due to the rarity and heterogeneity of CTCs in blood samples that could lead to misleading results from assays only based on single CTC counts. To address this issue, a feasible direction is to combine the CTC counts with other clinical data for analysis. Recent studies have demonstrated the use of this new strategy for early detection and prognosis evaluation of cancers, or even for the distinguishment of cancers with different stages. Overall, this approach could pave a new path to improve the technical problems in the clinical applications of CTC counting techniques. In this review, the information relevant to CTCs, including their characteristics, clinical use of CTC counting, and technologies for CTC enrichment, were first introduced. This was followed by discussing the challenges and new perspectives of CTC counting techniques for clinical applications. Finally, the advantages and the recent progress in combining CTC counts with other clinical parameters for clinical applications have been discussed.

Keywords: CTC counts; CTCs; cancer diagnosis; cancer prognosis; circulating tumor cells; clinical application; multiple parameter.

Figure 1

The overview of CTCs’ biology, isolation techniques, and clinical application of CTC. (A) CTCs detach from the primary tumor, enter the blood, and then undergo the stages of intravasation, circulation, and extravasation to reach the occurrence of distant metastasis of the tumor. (B) CTCs in the blood can be isolated through immunological and biophysical principles. Immunological methods include positive and negative screening, while biophysical methods include based-on-size, density, and dielectrophoresis. (C) The isolated CTCs can be used clinically as a biomarker and an effective tool for diagnosis, prognosis, and treatment monitoring. Created with Biorender. Abbreviations: DEP, dielectrophoresis.

Figure 2

A brief description of the combined analysis of CTC counts and cancer-related parameters in clinical practice.