Biomarkers for detecting colorectal cancer non-invasively: DNA, RNA or proteins?

Table 1 Non-invasive protein (including cytokine) biomarkers used for colorectal cancer detection

Study setting	Sample type	Marker type	Biomarker(s)	Sensitivity (or its range)	Specificity (or its range)	Ref.
Screening (reviewed)	Stool	Protein	Haemoglobin (FIT)	66.0%-74.0%	84.0%-95.0%	[31]
Case-control (reviewed)	Stool	Protein	M2-PK	68.0%-93.0%	70.0%-97.5%	[32,33]
Case-control	Stool	Protein	MMP 9	89.30%	91.20%	[34]
Case-control	Stool	Protein panel	Complement C3, Lactotransferrin, Haemoglobin subunit α1 and Haptoglobin	71.00%	95.00%	[35]
Case-control	Serum	Protein	CA11-19	98.00%	84.00%	[36]
Case-control	Serum	Protein (cytokine)	MIC-1 (GDF15)	43.80%	96.70%	[36]
Case-control	Serum	Protein (cytokine)	IL-6	28.0%-89.5%	46.0%-94.0%	[37]
Case-control	Serum	Protein (cytokine)	IL-8	70.00%	91.00%	[36]
Case-control	Serum	Protein (cytokine)	Growth-related gene product β1	56.10%	95.30%	[36]
Case-control	Serum	Protein	Cyr61	83.00%	97.00%	[38]
Case-control	Serum	Protein	Β6-integrin	69.80%	100.00%	[39]
Case-control (reviewed)	Serum	Protein	TIMP-1	52.0%-85.0%	60.0%-95.0%	[40]
Case-control	Serum	Protein	RBP4	74.90%	81.70%	[36]
Case-control	Serum	Protein	THBS2	64.90%	87.10%	[36]
Case-control	Serum	Protein	TFF3	74.20%	94.80%	[36]
Case-control	Serum	Protein	COL3A1	98.80%	69.10%	[36]
Case-control	Serum	Protein	COL10A1	63.00%	85.00%	[36]
Case-control	Serum	Protein	AZGP1	55.80%	85.00%	[36]
Case-control	Serum	Protein	Angiopoietin-2	79.30%	82.40%	[36]
Case-control	Serum	Protein	Kininogen	63.60%	65.90%	[36]
Case-control	Plasma	Protein	Melanotransferrin	48.20%	92.50%	[36]
Case-control	Serum	Protein panel	RBP4 and CEA	80.80%	91.20%	[36]
Case-control	Serum	Protein panel	TFF3 and CEA	89.40%	87.80%	[41]
Case-control	Serum	Protein panel	sDC-SIGN and sDC-SIGNR	98.70%	94.80%	[42]
Case-control	Serum	Protein panel	IGFBP-3 and CEA	75.00%	90.00%	[43]
Case-control	Serum	Protein panel	AZGP1, CEA and CA19-9	67.50%	82.50%	[36]
Case-control	Serum	Protein panel	IGFBP2, DKK3 and PKM2	73.00%	95.00%	[36]
Case-control	Plasma	Protein panel	BAG4, IL6ST, VWF, EGFR and CD44	73.00%	90.00%	[44]
Case-control, prospective	Serum	Protein panel	CEA, hs-CRP, CYFra21-1 and Ferritin	60.0%-70.0%	81.0%-89.0%	[45]

FIT: Faecal immunochemical test.

Table 2 Non-invasive DNA, messenger RNA and long non-coding RNA biomarkers used for colorectal cancer detection

Study setting	Sample type	Marker type	Biomarker(s)	Sensitivity (or its range)	Specificity (or its range)	Ref.
Screening	Stool	DNA mutation panel	3 K-ras mutations, 10 APC mutations, 8 p53 mutations, microsatellite instability marker BAT-26 and long DNA marker	51.60%	94.40%	[46]
Case-control	Stool	Panel including DNA mutation, DNA methylation, DNA amount and protein testing	K-ras mutation, methylation of Vimentin (VIM), BMP3, NDRG4 and TFPI2 genes, DNA measurement by β-actin assessment and HemoQuant test for haemoglobin	78.0%-85.0%	85.0%-90.0%	[47]
Screening	Stool	Panel including DNA mutation, DNA methylation, DNA amount and protein testing	K-ras mutation, BMP3 and NDRG4 promoter methylation, DNA measurement by β-actin assessment and test for haemoglobin (FIT)	92.30%	86.60%	[48]
Case-control	Stool	Methylated DNA	BMP3 gene	51.0%-84.0%	90.0%-100.0%	[49]
Case-control	Stool	Methylated DNA	CDKN2A gene	20.0%-40.0%	84.0%-100.0%	[49]
Case-control	Stool	Methylated DNA	ECAD gene	65.20%	88.00%	[49]
Case-control	Stool	Methylated DNA	FBN1 gene	72.00%	93.30%	[49]
Case-control	Stool	Methylated DNA	GATA 4/5 gene promoter	42.9%-71.0%	84.0%-95.0%	[49,50]
Case-control	Stool	Methylated DNA	HLTF gene	20.0%-37.5%	90.0%-92.6%	[49]
Case-control	Stool	Methylated DNA	HIC1 gene	42.30%	98.00%	[49]
Case-control	Stool	Methylated DNA	HPP1 gene	71.20%	57.10%	[49]
Case-control	Stool	Methylated DNA	ING1b gene	73.70%	95.00%	[49]
Case-control	Stool	Methylated DNA	ITGA4 gene	40.00%	96.80%	[49]
Case-control	Stool	Methylated DNA	MGMT gene	33.9-55.1%	52.0%-100.0%	[49]
Case-control	Stool	Methylated DNA	NDRG4 gene promoter	53.0%-92.0%	89.1%-100.0%	[49-51]
Case-control	Stool	Methylated DNA	P16INK4A gene	71.70%	86.00%	[49]
Case-control	Stool	Methylated DNA	PHACTR3 gene	55.0%-66.0%	95.0%-100.0%	[49]
Case-control	Stool	Methylated DNA	RASSF2 gene	45.30%	94.70%	[49]
Case-control	Stool	Methylated DNA	SDC2 gene	81.10%	93.30%	[52]
Case-control	Stool	Methylated DNA	SEPT9 gene	20.0%-84.8%	80.0%-94.5%	[49]
Case-control	Stool	Methylated DNA	SFRP1 gene	26.4%-89.0%	86.0%-95.5%	[49]
Case-control	Stool	Methylated DNA	SFRP2 gene	32.1%-94.2%	54.0%-100.0%	[49,51]
Case-control	Stool	Methylated DNA	SPG20 gene	80.2%-89.0%	99.0%-100.0%	[49,51]
Case-control	Stool	Methylated DNA	SNCA gene	83.90%	75.00%	[49]
Case-control	Stool	Methylated DNA	TFPI2 gene	63.3%-92.0%	79.0%-100.0%	[49-51]
Case-control	Stool	Methylated DNA	TP53 gene	56.30%	100.00%	[49]
Case-control	Stool	Methylated DNA	Vimentin (VIM) gene	32.6%-86.0%	82.0%-100.0%	[49-51]
Case-control	Stool	Methylated DNA	WIF1 gene	19.3%-60.4%	96.7%-99.4%	[49]
Case-control	Stool	Methylated DNA	XAF1 gene	55.90%	52.00%	[49]
Case-control	Stool	Methylated DNA panel	BMP3 and NDRG4 genes	98.00%	90.00%	[49]
Case-control	Stool	Methylated DNA panel	MGMT and XAF1 genes	73.50%	52.00%	[49]
Case-control	Stool	Methylated DNA panel	MGMT-B and SFRP2 genes	88.30%	91.20%	[49]
Case-control	Stool	Methylated DNA panel	RASSF1A and SFRP2 genes	75.00%	89.40%	[51]
Case-control	Stool	Methylated DNA panel	SNCA and FNB1 genes	84.30%	93.30%	[53]
Case-control	Stool	Methylated DNA panel	Vimentin (VIM) and SFRP2 genes	92.50%	91.20%	[53]
Case-control	Stool	Methylated DNA panel	AGTR1, WNT2 and SLIT2 genes	74.0%-78.0%	88.0%-89.0%	[49,50]
Case-control	Stool	Methylated DNA panel	ECAD, MGMT and P16INK4A genes	72.00%	88.00%	[49]
Case-control	Stool	Methylated DNA panel	ITGA4, SFRP2 and P16INK4A genes	70.00%	96.80%	[49]
Case-control	Stool	Methylated DNA panel	MGMT, CDKN2A and hMTH1 genes	55.00%	63.00%	[49]
Case-control	Stool	Methylated DNA panel	MGMT, MLH1 and Vimentin (VIM) genes	75.00%	86.50%	[49,51]
Case-control	Stool	Methylated DNA panel	SFRP2, HPP1 and MGMT genes	93.70%	77.10%	[49]
Case-control	Stool	Methylated DNA panel	WIF-1, ALX-4 and Vimentin (VIM) genes	25.00%	98.00%	[49]
Case-control	Stool	Methylated DNA panel	Vimentin (VIM), OMSR and TFPI2 genes	86.70%	87.60%	[49]
Case-control	Stool	Methylated DNA panel	SFRP2, GATA4/5, NRDG4 and Vimentin (VIM) genes	96.40%	65.00%	[49]
Case-control	Stool	Human DNA content	Total human DNA content	66.00%	89.80%	[54]
Case-control	Bowel Lavage Fluid	Methylated DNA panel	miR-124-3, LOC386758 and SFRP1 genes	82.00%	79.00%	[55]
Case-control	Intrarectally collected colorectal mucus	Human DNA content	Total human DNA content	60.40%	94.80%	[56]
Case-control	Serum/plasma	Methylated DNA	ALX4 gene	23.0%-90.7%	72.5%-100.0%	[57]
Case-control	Serum/plasma	Methylated DNA	APC gene	57.0%-86.5%	86.0%-92.1%	[57]
Case-control	Plasma	Methylated DNA	CDH1 (E-cadherin) gene	60.00%	84.00%	[55]
Case-control	Serum/plasma	Methylated DNA	SDC2 gene	87.0%-90.7%	72.5%-95.2%	[36,57]
Case-control	Serum/plasma	Methylated DNA	SEPT9 gene	47.1-95.6%	81.0%-96.7%	[36,57-62]
Case-control	Serum/plasma	Methylated DNA	SFRP2 gene	54.0%-69.4%	40.0%-98.7%	[57,63]
Case-control	Plasma	Methylated DNA	THBD (Thrombomodulin) gene	70.70%	80.30%	[51]
Case-control	Serum/plasma	Methylated DNA	TPEF gene	65.0%-81.0%	69.0%-90.0%	[57]
Case-control	Serum/plasma	Methylated DNA	VIM (Vimentin) gene	59.0%-90.7%	72.5%-93.0%	[57]
Case-control	Plasma	Hypomethylated DNA	LINE-1 transposable DNA element	65.80%	90.00%	[36]
Case-control	Serum/plasma	Methylated DNA panel	IKFZ and BCAT1 genes	62.1%-95.0%	92.0%-95.0%	[36,57]
Case-control	Serum	Methylated DNA panel	SEPT9 and SDC2 genes	86.50%	92.10%	[64]
Case-control	Serum/plasma	Methylated DNA panel	APC, MGMT, RASSF2A and WIF-1 genes	86.50%	92.10%	[57]
Case-control	Plasma	Methylated DNA panel	ALX4, BMP3, NPTX2, RARB, SDC2, SEPT9 and VIM genes	90.70%	72.50%	[63]
Case-control	Serum	ALU115 DNA content	Free ALU115 DNA content	69.20%	99.10%	[36]
Case-control	Serum	DNA integrity	ALU247/115 DNA integrity index	73.10%	97.30%	[36]
Case-control	Serum	Free DNA content	ALU-based cell-free DNA	64.50%	98.90%	[36]
Case-control	Whole blood	mRNA expression	TSPAN8 gene	83.60%	58.20%	[36]
Case-control	Whole blood	mRNA expression	LGALS gene	82.10%	61.20%	[36]
Case-control	Whole blood	mRNA expression	COL1A2 gene	73.10%	59.70%	[36]
Case-control	Whole blood	mRNA expression	CEACAM6 gene	65.70%	61.20%	[36]
Case-control	Whole blood or serum	mRNA expression	SALL4 gene	85.9%-96.1%	85.7%-95.0%	[65,66]
Case-control	Whole blood	mRNA expression panel	TSPAN8 and LGALS4 genes	92.50%	67.20%	[36]
Case-control (CRC and high-risk adenomas in the case group)	Whole blood	mRNA expression panel	LGALS4, CEACAM6, TSPAN8 and Col1A2 genes	75.00%	87.00%	[67]
Case-control	Whole blood	mRNA expression panel	CEA, EpCAM, CK19, MUC1, EGFR and C-Met genes	87.00%	85.00%	[68]
Case-control	Whole blood	Long non-coding RNA expression	NEAT1 variant 1	69.00%	79%	[36]
Case-control	Whole blood	Long non-coding RNA expression	NEAT1 variant 2	70.00%	96.00%	[36]
Case-control	Serum	Long non-coding RNA expression	BLACAT1	83.30%	76.70%	[69]
Case-control	Plasma	Long non-coding RNA expression panel	ATB and CCAT1	82.00%	75.00%	[70]
Case-control	Plasma	Long non-coding RNA expression panel	91H, PVT-1 and MEG3	82.80%	78.60%	[71]
Case-control	Serum	Long non-coding RNA expression panel	LOC285194, RP11-462C24.1 and Nbla12061	68.30%	86.90%	[72]

FIT: Faecal immunochemical test; CRC: Colorectal cancer.

Table 3 Non-invasive microRNA biomarkers used for colorectal cancer detection

Study setting	Sample type	Marker type	Biomarker(s) and detection methods	Sensitivity (or its range)	Specificity (or its range)	Ref.
Case-control	Stool	MicroRNA	miR-18a, upregulated	61.00%	69.00%	[73]
Case-control	Stool	MicroRNA	miR-20a, upregulated	55.00%	82.00%	[73]
Case-control	Stool	MicroRNA	miR-21, upregulated	56.0%-86.0%	73.0%-81.1%	[73,74]
Case-control	Stool	MicroRNA	miR-92a, upregulated	72.00%	73.00%	[73]
Case-control	Stool	MicroRNA	miR-106a, upregulated	34.00%	97.00%	[73]
Case-control	Stool	MicroRNA	miR-135b, upregulated	78.00%	68.00%	[73]
Case-control	Stool	MicroRNA	miR-144*, upregulated	74.00%	87.00%	[73]
Case-control	Stool	MicroRNA	miR-221, upregulated	62.00%	74.00%	[73]
Case-control	Stool	MicroRNA	miR-223, upregulated	77.00%	96.00%	[75]
Case-control	Stool	MicroRNA	miR-451, upregulated	88.00%	100.00%	[75]
Case-control	Stool	MicroRNA panel	miR-223 and mir-92a, both upregulated	97.00%	75.00%	[73]
Case-control	Stool	MicroRNA panel	miR-17-93 cluster and miR-135b, all upregulated	74.00%	79.00%	[73]
Case-control	Stool	MicroRNA panel	miR-144-5p, miR-451a and miR-20b-5p, all upregulated	66.00%	95.00%	[76]
Case-control	Plasma	MicroRNA	miR-17-3p, upregulated	64.00%	70.00%	[73,77]
Case-control	Plasma	MicroRNA	miR-18a, upregulated	73.10%	79.10%	[77]
Case-control	Plasma	MicroRNA	miR-20a, upregulated	46.00%	73.40%	[73,77]
Case-control	Serum/plasma	MicroRNA	miR-21, upregulated	65.0%-91.4%	74.4%-95.0%	[73,77-79]
Case-control	Plasma	MicroRNA	miR-24, downregulated	78.40%	83.80%	[77]
Case-control	Plasma	MicroRNA	miR-29a, upregulated	69.00%	89.10%	[77]
Case-control	Serum/plasma	MicroRNA	miR-29b, downregulated	61.4%-77.0%	72.5%-75.0%	[77]
Case-control	Plasma	MicroRNA	miR-92, upregulated	89.00%	70.00%	[77]
Case-control	Serum/plasma	MicroRNA	miR-92a, upregulated	65.5%-84.0%	71.2%-82.5%	[73,77]
Case-control	Plasma	MicroRNA	miR-96, upregulated	65.40%	73.30%	[73,77]
Case-control	Plasma	MicroRNA	miR-106a, upregulated	74.00%	44.40%	[77]
Case-control	Serum	MicroRNA	miR-139-3p, downregulated	96.60%	97.80%	[80]
Case-control	Serum	MicroRNA	miR-139a-5p, upregulated	76.70%	88.00%	[81]
Case-control	Plasma	MicroRNA	miR-155, upregulated	58.20%	95.00%	[73]
Case-control	Plasma	MicroRNA	miR-182, upregulated	78.00%	91.00%	[82]
Case-control	Serum	MicroRNA	miR-194, downregulated	72.00%	80.00%	[77]
Case-control	Serum	MicroRNA	miR-196b, upregulated	63.00%	87.40%	[84]
Case-control	Plasma	MicroRNA	miR-200c, upregulated	64.10%	73.30%	[77]
Case-control	Serum	MicroRNA	miR-210, upregulated	74.6%-88.6%	73.5%-90.1%	[77,79]
Case-control	Plasma	MicroRNA	miR-221, upregulated	86.00%	41.00%	[73,77]
Case-control	Plasma	MicroRNA	miR-320a, downregulated	92.80%	73.10%	[77]
Case-control	Serum	MicroRNA	miR-338-5p, upregulated	76.30%	92.50%	[84]
Case-control	Serum	MicroRNA	miR-372, upregulated	81.90%	73.30%	[77]
Case-control	Serum	MicroRNA	miR-375, downregulated	76.90%	64.60%	[77]
Case-control	Plasma	MicroRNA	miR-423-5p, downregulated	91.90%	70.80%	[77]
Case-control	Plasma	MicroRNA	miR-506, upregulated	76.80%	60.70%	[85]
Case-control	Plasma	MicroRNA	miR-601, downregulated	69.20%	72.40%	[77]
Case-control	Plasma	MicroRNA	miR-760, downregulated	80.00%	72.40%	[77]
Case-control	Serum	MicroRNA	miR-1290, upregulated	70.10%	91.20%	[86]
Case-control	Plasma	MicroRNA	miR-4316, upregulated	76.80%	75.00%	[85]
Case-control	Plasma	MicroRNA panel	miR-19a and miR-19b, both upregulated	78.60%	77.40%	[77]
Case-control	Serum	MicroRNA panel	miR-21 and miR-92a, both upregulated	68.00%	91.20%	[73,77]
Case-control	Plasma	MicroRNA panel	miR-29a and miR-92a, both upregulated	83.00%	84.70%	[73,77]
Case-control	Plasma	MicroRNA panel	miR-200c and miR-18a, both upregulated	84.60%	75.60%	[36,77]
Case-control	Plasma	MicroRNA panel	miR-223 and miR-92a, both upregulated	76.00%	71.00%	[73]
Case-control	Plasma	MicroRNA panel	miR-320d, downregulated; miR-1290, upregulated	81.20%	90.70%	[87]
Case-control	Plasma	MicroRNA panel	miR-431 and miR-139-p3, both upregulated	91.00%	57.00%	[77]
Case-control	Plasma	MicroRNA panel	miR-601 and miR-760, both downregulated	83.30%	69.10%	[73,77]
Case-control	Plasma	MicroRNA panel	miR-19a, miR-19b and miR-15b, all upregulated	78.60%	79.20%	[77]
Case-control	Plasma	MicroRNA panel	miR-24, miR-320a and miR-423-5p, all downregulated	92.80%	70.80%	[36,77]
Case-control	Plasma	MicroRNA panel	miR-144-3p, miR-425-5p and miR-1260b, all downregulated	93.80%	91.30%	[88]
Case-control	Serum	MicroRNA panel	miR-145, downregulated; miR-106a and miR-17-3p, upregulated	78.50%	82.80%	[73,77]
Case-control	Plasma	MicroRNA panel	miR-409-3p, upregulated; miR-7 and miR-93, downregulated	82.00%	89.00%	[73,77]
Case-control	Plasma	MicroRNA panel	miR-18a, miR-21, miR-22 and miR-25, all upregulated	67.00%	90.00%	[89]
Case-control	Serum	MicroRNA panel	miR-23a-3p, miR-27a-3p, miR-142-5p and miR-376c-3p, all upregulated	89.00%	81%	[36]
Case-control	Plasma	MicroRNA panel	miR-29a, miR-92a, upregulated; miR-601, miR-760, downregulated	83.30%	93.10%	[77]
Case-control	Serum	MicroRNA panel	miR-21, miR-29, miR-92, miR-125, miR-223, all upregulated	84.70%	98.70%	[78]
Case-control	Plasma	MicroRNA panel	miR-19a, miR-19b, miR-15b, miR-29a, miR-335, miR-18a, all upregulated	91.00%	90.00%	[90]
Case-control	Plasma	MicroRNA panel	miR-21, let-7g, upregulated, mir-31, mir-92a, miR-181b, miR-203, downregulated	96.00%	81.00%	[73]
Case-control	Plasma	MicroRNA panel	miR-103a-3p, miR-127-3p, miR-151a-5p, miR-17-5p, miR-181a-3p, miR-18a-5p, miR-18b-5p, all upregulated	76.90%	86.70%	[91]
Case-control	Plasma	Exosomal MicroRNA panel	miR-27a, miR-130a, both upregulated	82.50%	75.00%	[92]
Case-control	Saliva	MicroRNA	miR-21, upregulated	97.00%	91.00%	[93]

Table 4 Non-invasive volatile organic compounds and small metabolite biomarkers used for colorectal cancer detection

Study setting	Sample type	Marker type	Biomarker(s) and detection methods	Sensitivity (or its range)	Specificity (or its range)	Ref.
Case-control	Stool	VOCs	Hydrogen sulphide, Dimethylsulphide, Dimethyldisulphide, mlz 90 - detected by selected ion flow tube (SIFT) mass spectrometry (MS)	72.00%	78.00%	[94]
Case-control	Stool	VOCs	Propan-2-ol, 3-methylbutanoic acid - detected by gas chromatography (GC) and MS	87.90%	84.60%	[95]
Case-control	Stool	VOCs	Methyl mercaptan (increased) and hydrogen (decreased) – detected by GC	90.00%	57.70%	[96]
Case-control	Stool	VOCs	Pattern recognition technique - canine scent judgment	97.00%	99.00%	[97]
Case-control	Stool	VOCs	Pattern recognition technique (eNose Cyranose® 320)	85.00%	87.00%	[94]
Case-control	Stool	VOCs	Pattern recognition technique (SCENT A1)	95.00%	95.00%	[98]
Case-control	Urine	VOCs	Ion mobility spectroscopy technology (FAIMS)	88.00%	60.00%	[99]
Case-control	Urine	VOCs	Ion mobility spectroscopy technology (FAIMS)	63.00%	63.00%	[100]
Case-control	Urine	VOCs	Pattern recognition technique (eNose applied)	78.00%	79.00%	[99]
Case-control	Breath	VOCs	Pattern recognition technique - canine scent judgment	91.00%	99.00%	[97]
Case-control	Breath	VOCs	Acetone (increased), ethyl acetate (increased), ethanol (decreased) and 4-methyl octane (decreased) detected by GC-MS	85.00%	94.00%	[99]
Case-control	Breath	VOCs	Nonanal, decanal, 4-methyl-pentanone, 2-methylbutane, 4-methyloctane, 4-methylundecane, 2-methylpentane, methylcyclopentane, cycloxehane, methylcyclohexane, trimethyldecane-1,2-pentadiene, 1,3-dimethylbenzene, 1,4-dimethylbenzene – detected by GC-MS	86.00%	83.00%	[99]
Case-control	Stool	Magnetic resonance spectra	Magnetic resonance spectra patterns	85.20%	86.90%	[101]
Case-control	Stool	Small metabolites	Acetate – detected by proton magnetic resonance spectroscopy (PMRS)	94.70%	92.30%	[102]
Case-control	Stool	Small metabolites	Succinate – detected by PMRS	91.20%	93.50%	[102]
Case-control	Serum	Aromatic carboxylic acids	Benzoic acid – detected by CE-time of flight (TOF) MS	89.00%	82.00%	[103]
Case-control	Serum	Fatty acids	GTA-446 – detected by flow injection analysis MS	83.30%	84.80%	[104]
Case-control	Plasma	Amino acid metabolites	L-kynurenine – detected by high-performance liquid chromatography (HPLC)	85.20%	100.00%	[105]
Case-control	Plasma	Fatty acids	Decanoic acid – detected by CE-TOFMS	87.80%	80.00%	[106]
Case-control	Serum	Multiple metabolites	38 metabolites detected by GC-MS	85.00%	86.00%	[107]
Case-control	Serum	Phospholipids (sphingomyelins and phosphatidylcho-lines)	SM (34:1), PC (34:1), PC (34:2), PC (36:4), PC (36:2), PC (36:3) - detected by MS	♂77.3%; ♀80.8%	♂92.4%; ♀85.9%	[108]
Case-control	Serum	Unsaturated free fatty acids (panel)	C16:1, C18:3, C20:4, C22:6, all downregulated – detected by MS	93.80%	92.20%	[109]
Case-control	Serum	Amino acids (panel)	8 amino acids – detected by LC-MS/MS	65.00%	95.00%	[110]
Case-control	Serum	Amino acids, fatty acids, carbohydrates	13 metabolites – detected by LC-MS/MS	96.00%	80.00%	[111]
Case-control	Serum	Metabolite panel	2-hydroxy-butyrate, aspartic acid, kynurenine, cystamine – detected by GC-MS	83.10%	81.00%	[112]
Case-control	Serum	Lipid metabolites (panel)	Palmitic amide, oleamide, hexadecaneodioic acid, octadecanoic acid, eicosatrienoic acid, LPC(18:2), LPC(20:4), LPC(22:6), myristic acid, LPC(16:0) – detected by ion cyclotron resonance MS	98.10%	100.00%	[113]
Case-control	Serum	Panel of hydroxylated polyunsaturated ultra long-chain fatty acids	C28H46O4, C28H48O4 and C28H50O4, all downregulated – detected by LC-MS/MS and nuclear MR	75.00%	90.00%	[114]
Case-control	Serum	Multiple metabolites (panel)	11,14-eicosadienoic acid, 12a-hydroxy-3-oxocholadienic acid, 12-ketodeoxycholic acid, 12-keto-tetrahydro-leukotriene B4, 13-cis-retinoic acid, 1b-hydrocholic acid, 1-methylhistamine, 1-monopalmitin, 2,3-dihydroxybutanoic acid, 24-hydroxycalcitriol – detected by GC-TOFMS and UPLC-QTOFMS	83.70%	91.70%	[115]
Case-control	Plasma	Amino acids, fatty acids, carbohydrates	8 metabolites – detected by CT-TQMS	99.30%	93.80%	[116]
Case-control	Plasma	Choline-containing phospholipids (panel)	Total saturated lysophosphatidyl-cholines (LPCs), 18:2 LPC and sphingosylphosphorylcholine – detected by LC-MS/MS	88.30%	80.00%	[117]
Case-control	Plasma	Choline-containing phospholipids (panel)	Total saturated lysophosphatidyl-cholines (LPCs) and the difference between 18:2 LPC and 18:1 LPC – detected by LC-MS	82.00%	93.00%	[118]
Case-control	Dried blood	Amino acids and acylcarnitines (panel)	C16, Arg, C4/C8, C5/C3, Val, Phe/Tyr, Ala, C4/C3 – detected by direct infusion MS	81.20%	83.90%	[119]
Case-control	Urine	Polyamines	N1, N12-diacetylspermine – detected by ELISA	75.80%	96.00%	[120]
Case-control	Urine	Polyamines and amino acid metabolites	N1, N12-diacetylspermine and kynurenine – detected by LC-MS	80.00%	80.00%	[121]
Case-control	Urine	Amino acids and acetoacetate (panel)	Alanine, glutamine, aspartic acid and acetoacetate – detected by PMRS	87.50%	91.30%	[122]
Case-control	Urine	Nucleosides (panel)	5-hydroxymethyluracil and 8-oxo-7,8-dihydroguanine – detected by UPLC-MS/MS	78.60%	75.00%	[123]
Case-control	Urine	Nucleosides (panel)	Cytidine, 3-methylcitidine, 1-methyladenosine, 2-deoxyguanosine, adenosine, inosine – detected by HPLC-MS/MS	69.00%	98.00%	[124]
Case-control	Urine	Metabolite panel	Citrate, Hippurate, p-cresol, 2-aminobutyrate, myristate, putrescine and kynurenate - detected by UPLC-QTOFMS	97.50%	100%	[125]
Case-control	Urine	Nucleosides (panel)	Adenosine, N4-acetylcytidine, cytidine, guanosine, inosine, 1-methyladenosine, 1-methylguanosine, 1-methylinosine, 2-methylguanosine, 2,2-methylguanosine, N6-methyladenosine, uridine, 3-methyluridine+5-methyluridine, pseudouridine – detected by reverse phase HPLC	76.90%	90.40%	[126]
Case-control	Urine	Nucleosides (panel)	Adenosine, N4-acetylcytidine, cytidine, guanosine, inosine, 1-methyladenosine, 1-methylguanosine, 1-methylinosine, 2-methylguanosine, 2,2-methylguanosine, N6-methyladenosine, 5-methyluridine, pseudouridine, uridine – detected by column switching HPLC	71.00%	96.00%	[127]

Table 5 Non-invasive faecal bacterial biomarkers used for colorectal cancer detection

Study setting	Sample type	Marker type	Biomarker(s)	Sensitivity (or its range)	Specificity (or its range)	Ref.
Case-control	Stool	Bacterial	Fusobacterium nucleatum	54.0%-92.8%	79.8%-91.0%	[128-131]
Case-control	Stool	Bacterial	clbA-positive bacteria	56.4%	81.5%	[131]
Case-control	Stool	Bacterial panel	Fusobacterium nucleatum, Bacteroides clarus, Roseburia intestinalis and Clostridium hathewayi	92.8%	79.8%	[130]
Case-control	Stool	Bacterial panel	clbA-positive bacteria and Fusobacterium nucleatum	84.6%	63.1%	[131]
Case-control	Stool	Bacterial panel	Ratio of Fusobacterium nucleatum to Bifidobacterium	84.6%	92.3%	[132]
Case-control	Stool	Bacterial panel	Combination of ratios of Fusobacterium nucleatum to Bifidobacterium and Fusobacterium nucleatum to Faecalibacterium prausnitzii	90.0%	90.2%	[132]
Case-control (CRC and adenomatous polyps in the case group)	Stool	Bacterial panel	Fusobacterium nucleatum, Enterococcus faecalis, Streptococcus bovis, Enterotoxigenic Bacteroides fragilis, and Porphyromonas spp	91.4%	93.5%	[133]

CRC: Colorectal cancer.