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, Min Jung Kim1,2,3
, Ji Won Park1,2,3
, Seung-Yong Jeong1,2,3
1Department of Surgery, Seoul National University College of Medicine, Seoul, Korea
2Colorectal Cancer Center, Seoul National University Cancer Hospital, Seoul, Korea
3Seoul National University Cancer Research Institute, Seoul, Korea
© 2026 The Korean Society of Coloproctology
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Conflict of interest
No potential conflict of interest relevant to this article was reported.
Funding
None.
Author contributions
Conceptualization: all authors; Formal analysis: JYH, MJK; Investigation: JYH; Methodology: JYH, MJK; Supervision: MJK, JWP, SYJ; Visualization: JYH, MJK; Writing–original draft: JYH, MJK; Writing–review & editing: all authors. All authors read and approved the final manuscript.
| Pathogenic bacteria | Evidence | Reference |
|---|---|---|
| Fn | ||
| Mechanistic data | FadA binds E-cadherin → β-catenin/Wnt activation | [15] |
| LPS–TLR4/MYD88 signaling → NF-κB activation | [16] | |
| Fap2 binds TIGIT | [17] | |
| Induces chemotherapy resistance | ||
| Observational data | Enriched in CRC tissue/stool and linked to clinicopathologic features | [19] |
| Higher Fn burden is associated with worse outcomes in pooled analyses | [35] | |
| Interventional data | Metronidazole-mediated depletion of Fn lowers succinate level, restores the sensitivity to anti–PD-1 therapy, and suppresses tumor growth in CRC models | [36] |
| pks+ Escherichia coli | ||
| Mechanistic data | pks island encodes colibactin → induces DSB | [21] |
| Colibactin leaves a characteristic mutational signature | [18, 20, 22] | |
| Promotes genomic instability and epithelial barrier dysfunction | [23] | |
| Observational data | pks+ E. coli detected in human CRC tissue | [19] |
| Interventional data | Inhibition of colibactin peptidase blocks colibactin genotoxicity and reduces tumorigenesis in colonized mouse CRC models | [37] |
| ETBF | ||
| Mechanistic data | BFT cleaves E-cadherin and activates β-catenin/Wnt and inflammatory cascades | [24, 25] |
| Induces Th17/IL-17–dominant mucosal inflammation that promotes tumorigenesis | [26] | |
| Associated with epigenetic remodeling of colonic epithelium in experimental models | [27] | |
| Observational data | ETBF gene is prevalent in colonic mucosa of CRC patients and is associated with colorectal neoplasia | [19] |
| ETBF signals reproducibly detected in population datasets → stage-dependent patterns reported | [34] | |
| Interventional data | Clearing ETBF with cefoxitin in colonized mice reduces IL-17–dependent colon tumorigenesis | [38] |
| Pa | ||
| Mechanistic data | Activated SREBP2 increases cell proliferation via cholesterol biosynthesis | [28] |
| Binds to integrin α2/β1 via PCWBR2 → triggers inflammatory signaling | [29] | |
| Observational data | Bacteremia with Pa is linked to CRC diagnosis in retrospective cohorts | [39] |
| Interventional data | In mice, Pa supplementation promotes tumor growth; depletion/antibiotic approaches can restore anti–PD-1 efficacy in resistant models | [30] |
| Sgg | ||
| Mechanistic data | Induces inflammatory and pro-proliferative signaling in colon tissue | [33] |
| Observational data | Detected in CRC-associated microbiome profiles | [31] |
| Interventional data | In mice, Sgg colonization increases tumor burden and accelerates tumor progression | [32] |
CRC, colorectal cancer; Fn, Fusobacterium nucleatum; E-cadherin, epithelial cadherin; LPS, lipopolysaccharides; TLR4, Toll-like receptor 4; MYD88, myeloid differentiation primary response 88; NF-κB, nuclear factor–κB; TIGIT, T-cell immunoreceptor with immunoglobulin and ITIM (immunoreceptor tyrosine-based inhibitory motif) domains; PD-1, programmed death receptor 1; pks, polyketide synthase; DSB, double-strand break; ETBF, enterotoxigenic Bacteroides fragilis; BFT, Bacteroides fragilis toxin; Th17, T helper 17 cell; IL-17, interleukin 17; Pa, Peptostreptococcus anaerobius; SREBP2, sterol regulatory element-binding protein 2; PCWBR2, putative cell wall binding repeat 2; Sgg, Streptococcus gallolyticus subsp gallolyticus.
| Study | Cohort | Approach | Results | Implication |
|---|---|---|---|---|
| Wu et al. [65] (2021) | 1,056 Public fecal samples across multiple studies | Integrated cross-study analysis with confounder adjustment | Adenoma-stage signals can be reproducible across populations, supporting stool microbiome panels as an early detection | |
| Adenoma vs. control: AUC=0.80 | ||||
| Adenoma vs. CRC: AUC=0.89 | ||||
| External validation: AUC of 0.78 and 0.84 in two independent cohorts | ||||
| Su et al. [66] (2022) | 2,320 Metagenomic dataset with 9 phenotypes including CRC and adenoma | Multiclass machine learning on fecal metagenomes | AUROC, 0.90–0.99 | Propose the noninvasive model for disease screening/risk assessment and potentially for treatment-response monitoring |
| Sensitivity, 0.81–0.95 | ||||
| Specificity, 0.76–0.98 | ||||
| Metagenomic analysis from public datasets: AUROC, 0.69–0.91 | ||||
| Gao et al. [67] (2023) | Cross-cohort WMS, 750 samples | Comparison of multimodal features; emphasis on strain-level SNVs | SNV model (adenoma vs. control): | Provide a rationale of microbial SNVs for the early detection of CRC |
| AUC=0.89 | ||||
| Sensitivity=0.79 | ||||
| Specificity=0.85 | ||||
| MCC=0.74 | ||||
| Tito et al. [68] (2024) | 589 Patients across CRC stages; compared with 15 published studies | Quantitative microbiome profiling with rigorous confounder control | The strongest microbiome covariates were transit time, fecal calprotectin, and BMI | Stool biomarkers may reflect inflammation /transit/body composition rather than CRC itself |
| Total 4,439 participants | The diagnosis group was not associated with microbiota variation (univariate dbRDA R²=0.2%, adjusted P=0.22) | Absolute/quantitative profiling plus explicit covariate control is essential | ||
| Fn lost its apparent CRC-stage association after deconfounding (P>0.05) | ||||
| Piccinno et al. [69] (2025) | 3,741 Stool metagenomes from 18 cohorts | Large pooled meta-analysis with strain-level analyses | CRC prediction: AUC=0.85 | Large, pooled training improves cross-cohort performance |
| Tumor location signal: left-sided vs. right-sided CRC discrimination AUC=0.66 | Stool metagenomes carry location- and stage-linked signals | |||
| Périchon et al. [34] (2022) | Stool PCR cohort: | Targeted PCR and qPCR for 5 CRC-associated markers | ETBF detection: | Marker positivity is stage-dependent, multimarker, stage-aware panels |
| Control (n=25) | Control, 24.0% | ETBF’s higher detection at the adenoma stage may be useful for early-risk enrichment | ||
| Adenoma (n=23) | Adenoma, 56.5% | |||
| CRC (n=81) | CRC, 30.9% | |||
| Stage I/II, 34.6% | ||||
| Stage IV, 22.2% |
CRC, colorectal cancer; AUC, area under the curve; AUROC, area under the receiver operating characteristic curve; WMS, whole metagenome sequencing; SNV, single nucleotide variant; MCC, Matthews correlation coefficient; BMI, body mass index; dbRDA, distance-based redundancy analysis; Fn, Fusobacterium nucleatum; PCR, polymerase chain reaction; qPCR, quantitative polymerase chain reaction; ETBF, enterotoxigenic Bacteroides fragilis.
| Strategy | Mechanism | Current evidence and limitation | Reference |
|---|---|---|---|
| Dietary modulation and prebiotics | Promotes SCFA-producing beneficial bacteria | Epidemiological evidence for reduced CRC risk with high-fiber diets | [86] |
| → anti-inflammatory signaling, epithelial barrier protection, immune homeostasis | Randomized trials targeting adenoma/CRC recurrence largely negative or neutral | ||
| Currently lifestyle-level recommendation rather than a therapeutic intervention | |||
| Probiotics, synbiotics, and postbiotics | Introduces beneficial microbes or microbial metabolites | Consistent results at CRC mouse or organoid model | [75–77] |
| → reduces inflammation, improves gut barrier, suppresses CRC-related pathogens, modulates immune responses | Evidence from CRC patient lacking | ||
| FMT | Replaces dysbiotic microbiota with donor microbiota | Clinical evidence mainly from melanoma in improving immune checkpoint inhibitor response | [78–80] |
| → reprograms immune/metabolic tumor microenvironment; enhances immunotherapy responsiveness | CRC data limited, mainly small pilots/uncontrolled combination trials | ||
| Safety, donor screening, and long-term ecology concerns remain major barriers | |||
| Engineered/synthetic probiotics | Genetically modified bacteria selectively colonize tumors and release anticancer molecules or immunomodulators | Reduces adenoma burden in CRC mouse model | [81, 82] |
| Human evidence is currently limited and not CRC-specific | |||
| Antibiotics | Theoretical elimination of CRC-promoting pathogens or dysbiosis drivers | Not recommended as a CRC-preventive/therapeutic strategy | [83, 84] |
Cite this Article
| Pathogenic bacteria | Evidence | Reference |
|---|---|---|
| Fn | ||
| Mechanistic data | FadA binds E-cadherin → β-catenin/Wnt activation | [15] |
| LPS–TLR4/MYD88 signaling → NF-κB activation | [16] | |
| Fap2 binds TIGIT | [17] | |
| Induces chemotherapy resistance | ||
| Observational data | Enriched in CRC tissue/stool and linked to clinicopathologic features | [19] |
| Higher Fn burden is associated with worse outcomes in pooled analyses | [35] | |
| Interventional data | Metronidazole-mediated depletion of Fn lowers succinate level, restores the sensitivity to anti–PD-1 therapy, and suppresses tumor growth in CRC models | [36] |
| pks+ Escherichia coli | ||
| Mechanistic data | pks island encodes colibactin → induces DSB | [21] |
| Colibactin leaves a characteristic mutational signature | [18, 20, 22] | |
| Promotes genomic instability and epithelial barrier dysfunction | [23] | |
| Observational data | pks+ E. coli detected in human CRC tissue | [19] |
| Interventional data | Inhibition of colibactin peptidase blocks colibactin genotoxicity and reduces tumorigenesis in colonized mouse CRC models | [37] |
| ETBF | ||
| Mechanistic data | BFT cleaves E-cadherin and activates β-catenin/Wnt and inflammatory cascades | [24, 25] |
| Induces Th17/IL-17–dominant mucosal inflammation that promotes tumorigenesis | [26] | |
| Associated with epigenetic remodeling of colonic epithelium in experimental models | [27] | |
| Observational data | ETBF gene is prevalent in colonic mucosa of CRC patients and is associated with colorectal neoplasia | [19] |
| ETBF signals reproducibly detected in population datasets → stage-dependent patterns reported | [34] | |
| Interventional data | Clearing ETBF with cefoxitin in colonized mice reduces IL-17–dependent colon tumorigenesis | [38] |
| Pa | ||
| Mechanistic data | Activated SREBP2 increases cell proliferation via cholesterol biosynthesis | [28] |
| Binds to integrin α2/β1 via PCWBR2 → triggers inflammatory signaling | [29] | |
| Observational data | Bacteremia with Pa is linked to CRC diagnosis in retrospective cohorts | [39] |
| Interventional data | In mice, Pa supplementation promotes tumor growth; depletion/antibiotic approaches can restore anti–PD-1 efficacy in resistant models | [30] |
| Sgg | ||
| Mechanistic data | Induces inflammatory and pro-proliferative signaling in colon tissue | [33] |
| Observational data | Detected in CRC-associated microbiome profiles | [31] |
| Interventional data | In mice, Sgg colonization increases tumor burden and accelerates tumor progression | [32] |
| Study | Cohort | Approach | Results | Implication |
|---|---|---|---|---|
| Wu et al. [65] (2021) | 1,056 Public fecal samples across multiple studies | Integrated cross-study analysis with confounder adjustment | Adenoma-stage signals can be reproducible across populations, supporting stool microbiome panels as an early detection | |
| Adenoma vs. control: AUC=0.80 | ||||
| Adenoma vs. CRC: AUC=0.89 | ||||
| External validation: AUC of 0.78 and 0.84 in two independent cohorts | ||||
| Su et al. [66] (2022) | 2,320 Metagenomic dataset with 9 phenotypes including CRC and adenoma | Multiclass machine learning on fecal metagenomes | AUROC, 0.90–0.99 | Propose the noninvasive model for disease screening/risk assessment and potentially for treatment-response monitoring |
| Sensitivity, 0.81–0.95 | ||||
| Specificity, 0.76–0.98 | ||||
| Metagenomic analysis from public datasets: AUROC, 0.69–0.91 | ||||
| Gao et al. [67] (2023) | Cross-cohort WMS, 750 samples | Comparison of multimodal features; emphasis on strain-level SNVs | SNV model (adenoma vs. control): | Provide a rationale of microbial SNVs for the early detection of CRC |
| AUC=0.89 | ||||
| Sensitivity=0.79 | ||||
| Specificity=0.85 | ||||
| MCC=0.74 | ||||
| Tito et al. [68] (2024) | 589 Patients across CRC stages; compared with 15 published studies | Quantitative microbiome profiling with rigorous confounder control | The strongest microbiome covariates were transit time, fecal calprotectin, and BMI | Stool biomarkers may reflect inflammation /transit/body composition rather than CRC itself |
| Total 4,439 participants | The diagnosis group was not associated with microbiota variation (univariate dbRDA R²=0.2%, adjusted P=0.22) | Absolute/quantitative profiling plus explicit covariate control is essential | ||
| Fn lost its apparent CRC-stage association after deconfounding (P>0.05) | ||||
| Piccinno et al. [69] (2025) | 3,741 Stool metagenomes from 18 cohorts | Large pooled meta-analysis with strain-level analyses | CRC prediction: AUC=0.85 | Large, pooled training improves cross-cohort performance |
| Tumor location signal: left-sided vs. right-sided CRC discrimination AUC=0.66 | Stool metagenomes carry location- and stage-linked signals | |||
| Périchon et al. [34] (2022) | Stool PCR cohort: | Targeted PCR and qPCR for 5 CRC-associated markers | ETBF detection: | Marker positivity is stage-dependent, multimarker, stage-aware panels |
| Control (n=25) | Control, 24.0% | ETBF’s higher detection at the adenoma stage may be useful for early-risk enrichment | ||
| Adenoma (n=23) | Adenoma, 56.5% | |||
| CRC (n=81) | CRC, 30.9% | |||
| Stage I/II, 34.6% | ||||
| Stage IV, 22.2% |
| Strategy | Mechanism | Current evidence and limitation | Reference |
|---|---|---|---|
| Dietary modulation and prebiotics | Promotes SCFA-producing beneficial bacteria | Epidemiological evidence for reduced CRC risk with high-fiber diets | [86] |
| → anti-inflammatory signaling, epithelial barrier protection, immune homeostasis | Randomized trials targeting adenoma/CRC recurrence largely negative or neutral | ||
| Currently lifestyle-level recommendation rather than a therapeutic intervention | |||
| Probiotics, synbiotics, and postbiotics | Introduces beneficial microbes or microbial metabolites | Consistent results at CRC mouse or organoid model | [75–77] |
| → reduces inflammation, improves gut barrier, suppresses CRC-related pathogens, modulates immune responses | Evidence from CRC patient lacking | ||
| FMT | Replaces dysbiotic microbiota with donor microbiota | Clinical evidence mainly from melanoma in improving immune checkpoint inhibitor response | [78–80] |
| → reprograms immune/metabolic tumor microenvironment; enhances immunotherapy responsiveness | CRC data limited, mainly small pilots/uncontrolled combination trials | ||
| Safety, donor screening, and long-term ecology concerns remain major barriers | |||
| Engineered/synthetic probiotics | Genetically modified bacteria selectively colonize tumors and release anticancer molecules or immunomodulators | Reduces adenoma burden in CRC mouse model | [81, 82] |
| Human evidence is currently limited and not CRC-specific | |||
| Antibiotics | Theoretical elimination of CRC-promoting pathogens or dysbiosis drivers | Not recommended as a CRC-preventive/therapeutic strategy | [83, 84] |
CRC, colorectal cancer;
CRC, colorectal cancer; AUC, area under the curve; AUROC, area under the receiver operating characteristic curve; WMS, whole metagenome sequencing; SNV, single nucleotide variant; MCC, Matthews correlation coefficient; BMI, body mass index; dbRDA, distance-based redundancy analysis;
CRC, colorectal cancer; SCFA, short-chain fatty acid; FMT, fecal microbiota transplantation.