The most widely used method for CTC analysis is the CELLSEARCH® CTC Test, FDA approved in breast, colorectal and prostate cancer, where identification of CTCs broadly rely on EpCAM, despite evidence of considerable heterogeneity of EpCAM expression during the cell cycle, in different cell lines and a lack of EpCAM in cells undergoing epithelial-mesenchymal transition (EMT) [3,4,5]. This evidence concerns the gene EPCAM and prostate cancer.