Isolation and typing techniques for circulating tumor cells

Circulating tumor cells (CTCs) are tumor cells that detach from primary tumors or metastatic sites and enter the peripheral blood. As an important biomarker for liquid biopsy, their detection and analysis have offered a promising avenue in early diagnosis, treatment response monitoring, and prognosis evaluation of tumors. Given the extreme rarity and high heterogeneity of CTCs, efficient and accurate separation and typing have become a primary research focus. This article systematically reviews the mainstream technologies for CTC separation and enrichment, including positive/negative selection based on immune markers, size/deformation/charge separation based on physical properties, and emerging microfluidic platforms; Furthermore, we discuss subtyping strategies for CTC phenotypes and genotypes, encompassing the combined application of surface markers such as EpCAM, CK, Vimentin, gene mutation and copy number variation analysis, transcriptome and proteomic feature analysis, etc.; Additionally, we highlight advancements in functional evaluation techniques such as single-cell culture, metabolic labeling, and in vivo tracking which provide insights into the stemness, drug resistance, and metastatic propensity of CTCs. Finally, we explore the prospects of integrating artificial intelligence and multi omics in CTC typing, pointing out that despite rapid technological progress, challenges in standardization, detection sensitivity, and clinical validation remain significant hurdles to their routine translational application. The review aims to provide a technical framework and cutting-edge perspective for CTC research, and promote its application in personalized tumor management.