Circulating tumor cell clusters: What we know and what we expect (Review)

Abstract

The major cause of cancer-associated mortality is tumor metastasis, a disease that is far from understood. Many studies have observed circulating tumor cells (CTCs) in patients' circulation systems, and a few latest investigations showed that CTC clusters have a potentially high capacity of metastasis. The capture and analysis of CTC clusters offer new insights into tumor metastasis and can facilitate the development of cancer treatments. We reviewed the research history of the CTC clusters, as well as the technologies used for detecting and isolating CTC clusters. In addition, we discuss the characteristics of CTC clusters and their roles in tumor dissemination. Clinical relevance of CTC clusters was also implicated in currently limited data. Moving forward, the next frontier in this field is to develop more efficient capture methods and decipher conundrums of characterization of CTC clusters. This will ultimately identify the clinical value of CTC clusters as a biomarker and therapeutic target.

Liquid biopsy in breast cancer: A comprehensive review

“…The researchers then improved this device by creating a parallel MOFF device, called pMOFF, which entails four single‐parallel MOFF channels that can handle a larger volume of blood . Furthermore, EMT‐induced CTCs can be isolated from the blood as single cells or in clusters called circulating tumor micro emboli expressing mesenchymal genes . These subpopulations of CTCs in breast cancer could be tumorigenic, possibly inducing metastatic tumors in the bone, lung and liver .…”

AR‐V7 in circulating tumor cells cluster as a predictive biomarker of abiraterone acetate and enzalutamide treatment in castration‐resistant prostate cancer patients

“…Diagnosis of CTC clusters in prostate, lung, and breast cancers is associated with shorter survival. CTC clusters have been observed in patients with cancers of different origin and by using multiple technologies …”

Disseminated tumour cells in bone marrow are the source of cancer relapse after therapy

“…However, the inconsistency of these markers and the short half‐life of CTCs limit their application as diagnostic and prognostic biomarkers in the clinical setting. It has been considered that CTCs are singly suspended in the circulation, but the amount of CTC clusters can be underestimated due to the lack of appropriate detection methods . The survival rates of CTCs are highly variable, and EpCAM‐negative and CD44‐positive subsets exhibit quiescence properties and can initiate relapse or metastasis .…”