The semi-automated CellSearch system (Menarini Silicon Biosystems), which combines an epithelial cell adhesion molecule (EpCAM)-based CTC enrichment with a cytokeratin-based CTC detection, is the only U.S. Food and Drug Administration (FDA) approved assay for the enumeration of CTCs as a prognostic biomarker in breast, prostate, and colorectal cancer [14], but has not been approved for use in NSCLC patients. The gene discussed is EPCAM; the disease is colorectal cancer.