The CellSearch® (CS) (Menarini, Silicon Biosystems, Bologna, Italy), a known method for quantification of CTCs based on the expression of the epithelial cell adhesion molecule (EpCAM) and of keratin, is the first standardized system approved by the U.S. Food and Drug Administration for capturing and detection of CTCs derived from metastatic breast and prostate cancer as well as metastatic CRC [10, 16]. Here, EPCAM is linked to prostate cancer.