Immunoaffinity techniques are capable of achieving high capture purities and efficiencies.18 CellSearch® is such a platform and is the only technology approved by FDA to be used for the clinical analysis of liquid biopsies.20,21 This system depends on the expression of the epithelial cell adhesion marker (EpCAM) to detect CTCs.20 However, EpCAM is only expressed on tumor cells of epithelial origin, such as prostate and breast cancer cells. Here, EPCAM is linked to breast cancer.