Pathology of circulating tumor cells and the available capture tools (Review).

Circulating tumor cells (CTCs), are tumor cells that diffuse into the circulating blood and serve an important role in the progress of cancer. During the early stages of cancer, CTCs undergo an epithelial‑mesenchymal transition and obtain a more invasive phenotype. Subsequently, the tumor cells enter the circulating blood with the aid of immune cells, and enter a dormant state upon reaching distal organs. As the tumor progresses, metastasis may occur under certain conditions. The capture technologies available for CTCs are based on antibody‑based capture, or capture based on the physical properties of CTCs, as well as modern technologies that integrate both these methods. Emerging modern technologies have increased the accuracy and efficiency of tumor cell capture, and have thus improved our understanding of tumor cells, and the molecular mechanisms underlying their properties. CTCs serve an important role in disease progression, prediction of patient prognosis and individualized treatment.