Table 1.

CTC enrichment methods, organized by technology type.

Enrichment Subcategory	Technology	Selection Criteria	Main Features	References
Immunoaffinity—Positive selection	CellSearch	EpCAM and Pan-CK positive selection	FDA-Approved	[21,46,47]
	AdnaTest	Antibody cocktail	Immunomagnetic selection, followed by RT-PCR	[48]
	MACS	EpCAM	Magnetic beads for positive selection through EpCAM	[49]
	MagSweeper	EpCAM	High purity, 9 mL/h	[50]
	CTC-Chip	EpCAM	1–2 mL/h	[51]
Immunoaffinity—Negative selection	EasySep Human CD45 Depletion Kit	CD45	Easy-to-use, high-throughput	[52]
	MACS	CD45	Immunomagnetic selection	[53,54]
Biophysical	RosetteSep CTC Enrichment Cocktail	Density, Antibody Cocktail	Immunoaffinity assay, centrifugation	[55]
	OncoQuick	Density, Size	Isolation by intense centrifugation	[56]
	Ficoll-Paque	Density	Cheap, easy-to-use, centrifugation	[57]
	ISET	Size, Deformability	Fixed samples in membrane	[58,59,60]
	ScreenCell	Size, Deformability	Cheap, easy-to-use, membrane	[61,62]
	Parsortix	Size, Deformability	Viable cells retained by size	[63,64,65]
	Vortex	Size	No RBC lysis required, captures viable cells in suspension, easy-to-use	[45,66]
	DEPArray	Electrical Signature	Requires pre-enrichment, allows recovery and manipulation of viable cells	[67,68,69]
Functional Assays	EPISPOT	Protein secretion	Discriminates between viable and apoptotic CTCs using protein secretion	[44,70]