Table 2. Application value of CTCs/ctDNA/exosomes in CRC.

Material	Biomarkers	Potential clinical utility	Methods	References
CTCs	CK-19, EpCAM	Prognostic	CK19-Epispot and CellSearch™	[58]
	EpCAM	Predictive and prognostic	CellSearch™	[22, 23][59]
	CEA, CK19, and CK20	Prognostic	RT-PCR	[33]
	CEA/CK/CD133	Prognostic	RT-PCR	[34]
	EpCAM, CKs; VIM, TWIST1, AKT2, SNAI1	Prognostic	CanPatrolTM	[60]
	CD133, EpCAM, CD26, CD44v6	Prognostic(functional research)	Drug sensitivity analysis of CTC lines	[62]
	KRAS, BRAF, and PI3KCA	Prognostic	Label-free Vortex technology	[28]
	EpCAM	Screening high-risk stage II CRC patients	CellSearch™	[66]
ctDNA	Methylated SEPT9	Screening and early detection	Duplicate real-time PCRs	[45]
	APC, KRAS, TP53, and PI3KCA	Prognostic and therapy monitoring	BEAMing, real-time PCR	[39]
	A modest panel of 15 genes	Predictive	Safe-SeqS	[67]
	APC, KRAS, TP53	Predictive	Safe-SeqS	[68]
	Methylated WIF1 and NPY	Prognostic	dPCR	[69]
	Methylated ALU83, ALU244, OSMR, and SFRP1	Diagnostic and prognostic	ALU-based real-time PCR, methylation-specific real-time PCR	[70]
	KRAS	Therapy selection and monitoring	BEAMing, real-time PCR, and NGSeq,	[71]
	KRAS	Therapy selection and monitoring	BEAMing and real-time PCR	[7]
	KRAS, BRAF	Therapy selection and monitoring	Real-time PCR	[72]
	KRAS, NRAS, MET, ERBB2, FLT3, EGFR, and MAP2K1	Therapy selection and monitoring	dPCR and NGS	[74]
	KRAS, BRAF	Therapy selection and monitoring	ARMS-qPCR	[75]
Exosomes	miRNAs	Diagnostic	miRNA microarray analysis and qRT-PCR	[79]
	miRNAs	Prognostic	Microarray and CGH analysis and qRT-PCR	[80]
	Proteins	Diagnostic	Mass spectrometry and western blotting	[81]
	Proteins	Prognostic (function research)	Proteomics measurements and western blotting	[82]
	Microvesicles (Fas ligand and TNF)	Prognostic and therapeutic(function research)	Flow cytometry, western blotting, and immunoelectron microscopy	[89]