EPCAM and neoplasm: Additionally, many of the most widespread CTC assays use EpCAM antibodies to separate cells of epithelial (ie CTCs) and hematopoietic (ie leukocytes) origin,38 however, EpCAM-negative populations of tumor cells have been shown to have high brain metastatic potential23,61 and so the isolation of EpCAM-negative CTCs therefore requires alternate approaches.