Liquid biopsies in colorectal cancer screening and diagnosis

Table 1 Comparison of exosomal biomarkers for colorectal cancer diagnosis

Ref.	Biomarkers	Expression in CRC vs controls	Diagnostic performance (sensitivity/specificity/AUC)	Study size (CRC patients/HCs)	Validation status and key findings
Li et al[80], 2023	Exosomal miR-548am-5p	Upregulated	Not mentioned	Clinical tissues: 18 pairs of CRC and adjacent nontumor tissues	This study elucidates the oncogenic function of exosomal miR-548am-5p rather than establishing its clinical diagnostic value
Ogata-Kawata et al[81], 2014	Seven-miRNA Panel (e.g., let-7a, miR-1246, miR-23a)	Upregulated	Reported high sensitivity in ROC analysis. Specific AUC for the panel is not provided in the excerpt, but individual miRNAs like miR-1246 showed high diagnostic accuracy	Discovery: 88 CRC/11 HC; validation: 13 CRC	Preliminary validation in an independent set; miRNA levels decreased post-surgery, indicating tumor origin; the study provides early but promising evidence
Zhao et al[83], 2025	miR-205-5p	Downregulated	AUC for CRC vs HC: 0.873	157 CRC/135 HC/20 benign	Single-cohort study with a relatively large sample; expression was lower in CRC and early-stage patients, and increased postoperatively. Shows potential as a diagnostic biomarker
Wang et al[84], 2022	miR-377-3p and miR-381-3p	Downregulated	Combined (CRC vs HC): AUC = 0.886miR-377-3p: AUC = 0.826; miR-381-3p: AUC = 0.843	175 CRC/172 HC	Single-cohort study; the combination showed improved diagnostic performance; expression was downregulated in early-stage CRC
Han et al[85], 2021	Panel: MiR-15b, miR-16, miR-21, miR-31	Upregulated	CRC vs HC: Sensitivity: 95.06%, specificity: 94.44% CRC vs Adenoma: Sensitivity: 85.19%, specificity: 82.09%	Training: 123 CRC/150 HC; validation: 81 CRC/90 HC	Validated in an independent cohort; the panel demonstrated high and consistent diagnostic accuracy in both training and validation sets
Hu et al[86], 2018	Six exosomal lncRNAs (e.g., LNCV6_116109)	Upregulated	Individual AUCs ranged from 0.650 to 0.770	50 CRC/50 HC	Proof-of-concept study; provides preliminary AUC values for individual lncRNAs, suggesting their potential as noninvasive biomarkers; requires further validation
Du et al[87], 2022	Panel: MiR-654-5p, miR-126, miR-10b, miR-144	miR-654-5p, -126, -10b upregulated; miR-144 downregulated	The diagnostic model based on this 4-miRNA signature achieved an AUC of 0.913 in the clinical validation cohort	88 CRC/11 HCclinical; validation: 100 CRC/120 HC	Validated in an independent clinical cohort; the signature was identified via machine learning and showed high diagnostic potential in validation
Zhang et al[88], 2024	miR-99b-5p and miR-409-3p[88]	Upregulated	For early CRC: miR-99b-5p alone: AUC = 0.735, sensitivity: 72.7%, specificity: 78.3%miR-99b-5p + miR-409-3p: AUC = 0.741, sensitivity: 77.3%, specificity: 78.3% + CEA: AUC = 0.812, sensitivity: 90.9%, specificity: 65.2%	68 CRC/27 HC	Single-cohort study; the study highlights the value of combining exosomal miRNAs with the traditional protein marker CEA to significantly boost sensitivity for early CRC detection

CRC: Colorectal cancer; AUC: Area under the curve; HC: Healthy control; ROC: Receiver operating characteristic; CEA: Carcinoembryonic antigen; miRNA: Micro RNA.

Table 2 Comparison of components in liquid biopsy

	CTCs	ctDNA	TEPs	Exosomes	RNA
Detection methods	CellSearch system, immunomagnetic bead enrichment, membrane filtration method	dPCR, next-generation sequencing, methylation sequencing, ARMS-PCR	Supercritical centrifugation, size exclusion chromatography, immune affinity capture	Ultra-high speed centrifugation, SEC, commercial extraction kits, microfluidic technology	qRT-PCR, dPCR, transcriptome sequencing
Representative biomarkers	EpCAM, CK8/18/19; CD44, CD133, ALDH1	KRAS, NRAS, BRAF, TP53; SEPT9, SDC2, VIM; MSI/MMR status	EGFR, EpCAM; vesicle-associated miRNAs	CD9, CD63, CD81; miR-92a, EGFR	miRNA, circRNA, lncRNA
Advantages	Obtain comprehensive tumor cell information, directly reflecting phenotype, stemness, and metastatic potential	The detection technology is mature with high standardization and excellent sensitivity	Stability superior to free nucleic acids with stable content	Long blood half-life and high stability	High sensitivity with a wide range of biomarkers
Limitations	Low abundance in peripheral blood, platform variability, and complex biological characteristics such as EMT	Early CRC exhibits extremely low abundance	No unified gold standard for separation and purification	Lack of unified separation criteria makes purity control difficult	Free RNA is highly susceptible to degradation, requiring stringent sample processing protocols
Clinical evidence level	Moderate to high level of evidence	High-quality evidence	Limited clinical evidence	Preclinical translational phase	Moderate evidence
Study size and validation cohort	Prospective large cohort studies on early CRC are insufficient	Predominantly prospective cohort	Lack of multicenter prospective validation	Multicenter validation cohort scarcity	The multicenter independent validation cohort requires refinement

CTC: Circulating tumor cell; ctDNA: Circulating DNA; TEP: Tumor-educated platelet; dPCR: Digital polymerase chain reaction; ARMS-PCR: Amplification-refractory mutation system polymerase chain reaction; qRT-PCR: Quantitative reverse transcription polymerase chain reaction; SEC: Size exclusion chromatography; EpCAM: Epithelial cell adhesion molecule; ALDH1: Aldehyde dehydrogenase 1; MSI: Microsatellite instability; MMR: Mismatch repair; EGFR: Epidermal growth factor receptor; circRNA: Circular RNA; lncRNA: Long noncoding RNA; EMT: Epithelial mesenchymal transition; CRC: Colorectal cancer; miRNA: Micro RNA.