Microbiome Signatures in Blood and Gut Emerge as Promising Biomarkers for Colorectal Cancer Detection
核心洞察
Researchers identified distinct stage-specific fecal and salivary microbiota signatures during colorectal cancer (搜索) progression, with fecal bacterial biomarkers achieving 93.16% diagnostic accuracy in distinguishing between healthy controls, non-metastatic, and metastatic CRC (搜索) patients.
A separate study developed an integrated serum bacterial DNA and metabolomics panel combining Firmicutes (搜索) abundance and threonic acid levels that demonstrated outstanding diagnostic performance with 95% accuracy, 94.1% sensitivity, and 90% specificity for CRC (搜索) detection.
Both studies revealed significant oral-to-gut microbiota translocation during cancer progression, with salivary bacteria comprising 14.9% of fecal microbiota in metastatic patients compared to only 1.7% in healthy controls, suggesting a novel mechanism of cancer-associated dysbiosis.
Two groundbreaking studies have revealed the potential of microbiome signatures as non-invasive biomarkers for colorectal cancer (搜索) (CRC (搜索)) detection, offering new hope for early diagnosis of the world's second leading cause of cancer-related death.
Fecal and Salivary Microbiota Signatures Show Stage-Specific Changes
A comprehensive study analyzing 90 participants from the First Affiliated Hospital of Zhejiang Chinese Medical University (搜索) identified distinct microbiota patterns that evolve throughout colorectal cancer (搜索) progression. The research, which included 30 metastatic CRC (搜索) patients, 30 non-metastatic CRC (搜索) patients, and 30 healthy controls, revealed significant alterations in both fecal and salivary bacterial communities.
The fecal microbiota analysis showed progressive changes along the healthy-to-metastatic cancer spectrum. Metastatic CRC (搜索) patients exhibited a considerably lower average Firmicutes (搜索) composition (45.68%) compared to non-metastatic patients (51.18%) and healthy controls (52.94%), while showing increased proportions of Actinobacteriota (搜索) (12.05% vs. 5.83% in non-metastatic and 5.73% in controls).
At the genus level, Bacteroides (搜索) showed an increasing proportion along the progression sequence (10.92% in controls vs. 11.44% in non-metastatic vs. 16.45% in metastatic patients), while beneficial bacteria like Prevotella_9 (搜索) were significantly depleted in cancer patients (13.24% in controls vs. 0.97% in non-metastatic vs. 5.12% in metastatic patients).
Oral-Gut Microbiota Translocation Intensifies During Cancer Progression
One of the most striking findings was the evidence of oral-to-gut microbiota translocation during CRC (搜索) progression. Source Tracker analysis detected salivary bacteria in the fecal microbiota of 63.3% of metastatic patients, 50.0% of non-metastatic patients, and 46.7% of healthy controls. More importantly, salivary bacteria constituted 14.9% of the fecal microbiota in metastatic patients, progressively decreasing to 3.2% in non-metastatic patients and 1.7% in healthy controls.
This translocation appears to drive gut dysbiosis during CRC (搜索) progression, potentially exacerbating fecal microbial network instability. The research showed that fecal microbiota networks demonstrated reduced stability when disease progressed, while salivary microbial networks exhibited increasing connectivity.
Diagnostic Performance Exceeds 90% Accuracy
Using machine learning approaches, researchers developed a three-class random forest model based on the top 8 fecal bacterial biomarkers that achieved remarkable diagnostic performance. The model attained an overall test accuracy of 78.95% with receiver operating characteristic (ROC) analysis yielding a macro-averaged area under curve (AUC) of 93.16%. Specifically, the model achieved 92.71% AUC for healthy controls, 90.15% for non-metastatic CRC (搜索), and 96.63% for metastatic CRC (搜索) detection.
Serum-Based Integrated Panel Achieves Outstanding Performance
A parallel study from San Carlos Hospital (搜索) in Madrid developed an innovative approach combining serum bacterial DNA analysis with metabolomics. This research, involving 43 CRC (搜索) patients and 21 controls, identified a simplified two-component diagnostic panel.
The integrated panel combined the relative abundance of Firmicutes (搜索) bacteria in serum with threonic acid concentration, achieving outstanding diagnostic accuracy with an AUC of 0.95, sensitivity of 94.1%, and specificity of 90%. This performance significantly exceeded individual biomarkers, with Firmicutes alone achieving 0.85 AUC and threonic acid alone reaching 0.78 AUC.
Serum Microbiome Reveals Cancer-Specific Signatures
The serum microbiome analysis revealed distinct taxonomic differences between CRC (搜索) patients and controls. While healthy controls showed preponderance of Proteobacteria (搜索) and higher percentages of Actinobacteriota (搜索), CRC patients exhibited decreased proportions of these phyla and increased presence of Firmicutes (搜索) and Bacteroidota (搜索).
The Firmicutes (搜索) to Bacteroidota (搜索) ratio, an established marker of dysbiosis, was notably higher in CRC (搜索) patients (1.41) compared to controls (1.01). Nine bacterial phyla showed differential abundance in CRC patients, with Firmicutes and Verrucomicrobiota (搜索) increased, while seven phyla including Proteobacteria (搜索), Bdellovibrionota, and Myxococcota were decreased.
Metabolomic Changes Reflect Cancer Metabolism
The metabolomic analysis identified 27 significantly different metabolites between CRC (搜索) patients and controls. Threonic acid, a metabolite of vitamin C degradation, emerged as the key discriminatory metabolite after adjusting for confounders. The increase in threonic acid concentration in CRC patients may derive from vitamin C catabolism caused by oxidative conditions associated with cancer.
Clinical Implications and Future Directions
These findings represent a significant advancement in non-invasive CRC (搜索) detection, addressing the critical need for alternatives to colonoscopy, which only 14% of high-risk populations in China undergo due to cost, invasiveness, and preparation requirements. The microbiome-based approaches could enable earlier detection, as up to 60% of CRC patients currently exhibit metastasis at diagnosis, correlating with poor prognosis and 5-year survival rates below 20%.
The research also opens new therapeutic avenues. The identification of specific oral pathobionts that colonize the gut during cancer progression suggests that targeted interventions against key oral bacteria may halt CRC (搜索) progression by restoring gut ecological balance. Additionally, the stage-specific translocation signatures could enable liquid biopsy approaches for early metastasis risk stratification.
Both studies acknowledge limitations including relatively small sample sizes and the need for external validation in multicenter cohorts. However, the consistent findings across different sample types (fecal, salivary, and serum) and analytical approaches strengthen the evidence for microbiome-based CRC (搜索) diagnostics.
The integration of multiple omics approaches demonstrates superior diagnostic performance compared to individual biomarkers, reinforcing the value of comprehensive molecular profiling in cancer detection. As the field moves toward precision medicine, these microbiome signatures could complement existing genetic markers to provide more thorough molecular characterization for both diagnosis and therapeutic target identification.