EpCAM-based assay is unable to detect CTCs with low or absent EpCAM expression and other circulating tumor associated cells, including stem cell-like tumor cells and CTCs undergoing epithelial–mesenchymal transition (EMT), which were identified by stem cell and EMT markers in early and metastatic breast cancer patients [11,12,13]; and cancer associated macrophage-like cells (CAMLs), which are specialized phagocytic myeloid cells found in the peripheral blood of patients with solid tumors including breast cancer, but not in healthy individuals [14]. The gene discussed is EPCAM; the disease is breast cancer.