Fig. 1.

The roles of CTC in tumor metastasis and the current applications of CTC technologies. Tumor cells translocate from the primary tumor and invade into the bloodstream to become CTCs. Most CTCs affected by microenvironment and undergo apoptosis. Some CTCs undergo phenotypic changes after EMT and finally forming metastases. CTCs are preliminary enriched from whole blood sample via different enrichment techniques. Different detection technologies such as CTC count, phenotypic analysis and single cell analysis can help with early detection, prognostication, chemotherapy, target therapy of patients