EPCAM and prostate cancer: The clinical gold standard is the CellSearch® System (Menarini-Silicon Biosystems, Huntingdon Valley, PA, USA), which immunomagnetically enriches EpCAM-positive CTCs using anti-EpCAM ferrofluid beads, followed by cytokeratin staining and CD45 exclusion; it received FDA approval for metastatic breast cancer [23], colorectal cancer [24], and prostate cancer [25].