EPCAM and colorectal carcinoma: Although targeting EpCAM on CTCs from CRC (epithelial origin) seems to be the best option to distinguish between CTCs and normal blood cells with mesenchymal phenotypes, the overreliance on a single specific CSM resulted in a selection bias [79], where only CTCs that predominantly retain epithelial characteristics (high EpCAM levels) are enriched, excluding a subpopulation of CTCs with mesenchymal traits (low or no EpCAM expressed) [85,86,87].