Cancer. Circulating tumor cells

Abstract

Much remains to be learned about CTCs and their clinical potential as biomarkers and therapeutic targets.

Hurdles and solutions in CTC research. Biophysical factors that may diminish the detection of CTCs include (A) filtration of large CTCs in smaller capillaries, (B) clustering of tumor cells that lodge in capillaries, and (C) cloaking of CTCs by platelets or coagulation factors. Biological factors that likely complicate the detection and isolation of clinically relevant populations of CTCs that currently rely on epithelial markers include (D) the presence of benign circulating epithelial cells, (E) the large heterogeneity among CTCs, (F) the possible stemness of a subpopulation of CTCs, (G) the (partial) epithelial-mesenchymal transition (EMT) that some CTCs undergo during dissemination, and (H) the unclear seeding potential of detected CTCs. Future research should use technologies focused on (I) improving the detection and isolation of CTCs, and (J) single-cell “omics.”