In flow cytometry, CTCs are identified and quantified using fluorescently labeled antibodies against proteins such as EpCAM or HMW-MAA/MCSP.15 Antibodies against other tumor or organ-specific markers may also be employed in CSF analysis.19 One advantage of flow cytometry is that it can be performed using standard flow cytometry equipment already available in many clinical laboratories. Here, EPCAM is linked to neoplasm.