Tracking cancer progression: from circulating tumor cells to metastasis

Abstract

The analysis of circulating tumor cells (CTCs) is an outstanding tool to provide insights into the biology of metastatic cancers, to monitor disease progression and with potential for use in liquid biopsy-based personalized cancer treatment. These goals are ambitious, yet recent studies are already allowing a sharper understanding of the strengths, challenges, and opportunities provided by liquid biopsy approaches. For instance, through single-cellresolution genomics and transcriptomics, it is becoming increasingly clear that CTCs are heterogeneous at multiple levels and that only a fraction of them is capable of initiating metastasis. It also appears that CTCs adopt multiple ways to enhance their metastatic potential, including homotypic clustering and heterotypic interactions with immune and stromal cells. On the clinical side, both CTC enumeration and molecular analysis may provide new means to monitor cancer progression and to take individualized treatment decisions, but their use for early cancer detection appears to be challenging compared to that of other tumor derivatives such as circulating tumor DNA. In this review, we summarize current data on CTC biology and CTC-based clinical applications that are likely to impact our understanding of the metastatic process and to influence the clinical management of patients with metastatic cancer, including new prospects that may favor the implementation of precision medicine. Publisher's NoteSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Discrimination between Breast Cancer Cells and White Blood Cells by Non-Invasive Measurements: Implications for a Novel In Vitro-Based Circulating Tumor Cell Model Using Digital Holographic Cytometry

“…Recent developments in microfluidic methods have allowed a number of new investigations related to CTCs; however, the low frequency of CTCs in the circulation remains a challenge for the application of CTC-based technologies in the clinical setting [45]. DHC could, in combination with machine-learning algorithms, distinguish between normal skin cells and melanoma cells, and between primary and metastatic melanoma cell lines with high significance [46].…”

EMT-Associated Heterogeneity in Circulating Tumor Cells: Sticky Friends on the Road to Metastasis

“…Circulating tumor cells (CTCs) contain the physical entities that cause metastases and therefore hold a special place in the era of liquid biopsies [1][2][3][4]. Although tumor biopsy is still the gold standard for cancer diagnosis of solid tumors, it is an invasive act both at the primary and metastatic sites, and it represents a snapshot during the progression of the disease.…”

MYC as a Multifaceted Regulator of Tumor Microenvironment Leading to Metastasis

“…Furthermore, OPN is important for the circulating tumor cells as it helps to evade immune cells by suppressing immune responses [ 205 , 206 , 207 ]. Recent data shows that MYC is also over-expressed in circulating tumor cells (CTSs), suggesting that its target genes could be essential for the survival of cancer cells in the bloodstream [ 208 ].…”