Circulating tumor cells (CTCs) as a liquid biopsy material and drug target.

Circulating tumor cells (CTCs) have attracted interest as biomarkers of cancer metastases but only recently has a reliable method of CTC detection been developed. CTCs can be thought of as a liquid biopsy from the blood, and they can be used in pathological and molecular assays. CTCs may ideally replace metastatic tissue biopsies in the prediction and monitoring of therapeutic responses and tumor recurrence. CTCs can be used to guide therapeutic cancer management and serve as drug targets. For this reason, the potential of this technology and the limitations of currently available methods of CTC detection are addressed here. The clinical applications of CTCs include the prediction of cancer prognosis; selection and monitoring of therapeutic regimens; and drug target applications. The manner in which CTC molecular profiling can facilitate prognosis and the selection of cancer therapies.