Enrichment and single-cell analysis of circulating tumor cells

TLDR

Metastatic cancer causes up to 90 % of cancer deaths, and circulating tumor cells (CTCs) are key mediators of metastasis; however, their extreme rarity and heterogeneity make liquid‑biopsy analysis challenging, prompting the development of diverse enrichment and single‑cell profiling technologies. This review seeks to comprehensively examine CTC analysis, outlining isolation strategies grounded in physical and biochemical capture methods and detailing single‑cell genomic, proteomic, and phenotypic profiling, while highlighting emerging trends and future research directions. The authors survey a range of CTC enrichment techniques—including size‑based, density‑gradient, immunocapture, and microfluidic approaches—and single‑cell analytical platforms such as single‑cell sequencing, proteomics, and phenotypic assays to assess tumor heterogeneity.

Abstract

Up to 90% of cancer-related deaths are caused by metastatic cancer. Circulating tumor cells (CTCs), a type of cancer cell that spreads through the blood after detaching from a solid tumor, are essential for the establishment of distant metastasis for a given cancer. As a new type of liquid biopsy, analysis of CTCs offers the possibility to avoid invasive tissue biopsy procedures with practical implications for diagnostics. The fundamental challenges of analyzing and profiling CTCs are the extremely low abundances of CTCs in the blood and the intrinsic heterogeneity of CTCs. Various technologies have been proposed for the enrichment and single-cell analysis of CTCs. This review aims to provide in-depth insights into CTC analysis, including various techniques for isolation of CTCs with capture methods based on physical and biochemical principles, and single-cell analysis of CTCs at the genomic, proteomic and phenotypic level, as well as current developmental trends and promising research directions.