EPCAM and cancer: By identifying a threshold of 5 CTCs detected in 7.5 mL of peripheral venous blood by EpCAM-based immunomagnetic capture followed by immunostaining for cytokeratins (CellSearch® System), it was shown that CTC count at baseline and increased levels of CTCs at any time point during treatment are strongly associated with higher risk of disease progression and cancer-related death compared to patients with less than 5 CTCs [107,108].