After EMT, the surface expression of EpCAM is significantly downregulated [4,5,6,7,16]. Due to the heterogeneous nature of CTCs, clinically meaningful CTCs closely relevant to cancer metastasis or cancer progression might be missed if conventional positive selection-based CTC isolation methodologies (e.g., CellSearch) are used [5,6,7,16]. This evidence concerns the gene EPCAM and cancer.