Isolation of circulating tumor cells: recent progress and future perspectives

Abstract Circulating tumor cells (CTCs) are cancer cells that shed from the primary tumor and enter into body fluids of the patient, where they travel to distant sites and ultimately form metastasis. Understanding the biology of CTCs, in particular at the critical stages of their itinerary, holds promises for better cancer cure. Since the beginning of this century, liquid biopsy has steadily grown to be a keen area of research due to its non-invasive features. As one of the most promising tumor biomarkers, CTCs have shown great potential in cancer diagnosis, prognosis, treatment response monitoring, and the exploration of biological mechanisms. Although various types of isolation and detection technologies emerge constantly, the rarity and heterogeneity of CTCs still pose huge challenges for these methods and make them inefficient. In addition, the clinical practice of different technologies still lacks reasonable and uniform standards. In this review, we provide a detailed overview of the isolation and enrichment strategies of CTCs, as well as their advantages and limitations. By summarizing the current status and suggesting future areas of CTCs research, we hope to continue the concerted effort for pushing forward the clinical application of CTCs, which may represent a paradigm shift for cancer theranostics in the future. Graphical Abstract