Table 1.

Comparison of protein-based and nucleic acid-based approaches for circulating tumor cell characterization in patient samples.

Type	Approach	Sample Volume Requirement *	Ability for CTC Quantification	High Specificity	High Sensitivity	Labor-Intensive/Challenging	Down-Stream Analysis
Protein-Based	Immunofluorescence	Small	Yes	Yes	No	Yes	Yes
	Flow Cytometry	Medium	Yes	Yes	No	Yes	Yes
	CellSearch®	Large	Yes	Yes	Yes	No	No
	CTC-Chip/iChip	Large	Yes	Yes	Yes	Yes	Yes
	AdnaTest	Large	No	Yes	Yes	No	No
	Isoflux	Large	Yes	Yes	Yes	No	Yes
Nucleic Acid-Based	RT-PCR	Small	No	No	Yes	No	No
	qRT-PCR	Small	No	No	Yes	No	No
	Next-Gen Sequencing	Small	No	Yes	Yes	Yes	Yes

* Small: ≥100 µL, Medium: ≥1 mL, Large: ≥7 mL.