Colorectal cancer appears to stand apart from other cancers in a surprising way. New research led by the University of East Anglia reports a distinct microbial “fingerprint” in colorectal tumors – a pattern not seen across the other cancer types studied. If borne out in clinical workflows, the finding could reshape how health systems use genome sequencing data already being generated for cancer care.
The work draws on large-scale whole genome sequencing (WGS) and links microbial DNA traces within tumor samples to clinical features. The study is published in Science Translational Medicine and uses data generated through national sequencing infrastructure, including the UK’s Genomics England program.
A distinct microbial signal in colorectal tumors
“This study changes how we think about the role of microbes in cancer,” said lead researcher Dr. Abraham Gihawi, from UEA’s Norwich Medical School.
The analysis identified a clear and reproducible microbial community unique to colorectal cancer. In contrast, other tumor types examined did not show a comparably distinct signature.
- Colorectal cancer stands out among the cancers evaluated for harboring a consistent, classifiable microbial community within tumor samples.
- This signal, if validated prospectively, could support diagnostic triage and research into tumor-microbe interactions without additional invasive procedures.
“Our results show that only colorectal tumors possess distinctly identifiable microbial communities.
“We found that these microbial signatures were so specific that they could accurately distinguish colorectal tumors from other tumors. We hope that this could help doctors diagnose the disease more precisely and researchers to study the microbes found in colorectal cancer.”
Colorectal cancer is already one of the most commonly diagnosed cancers worldwide and a leading cause of cancer deaths, particularly in high‑income countries, underscoring why any improvement in early and accurate detection carries system‑level consequences for screening programmes and treatment planning.
How the team probed tumor DNA for microbial clues
By analyzing tumor WGS data, the researchers leveraged the fact that sequencing captures not only human DNA but also non-human reads originating from bacteria and viruses within the sample matrix.
“When you collect cancer DNA sequences, you also gain information from the DNA of microbes contained within the samples,” said Dr. Gihawi.
“We wanted to determine the precise DNA composition of microbes present in each sample. So, we developed computer programs to remove human DNA and analyse the remaining microbe DNA.
“We then correlated this information with clinical data from the patients about their cancer type and clinical outcome.
“What we found challenges previous claims that each cancer type has a distinct microbiological signature or fingerprint.
“But importantly, as whole genome sequencing becomes more common in hospitals, we show that looking at the microbes in tumor samples could become a powerful tool for improving cancer care at little extra cost.
- Scale and scope
- Patients analyzed: more than 9,000.
- Tumor samples evaluated: 11,735 across 22 cancer types.
- Modality: whole genome sequencing with computational filtering of human reads to profile residual microbial DNA.
- Signal quality safeguards
- Computational decontamination to minimize human DNA carryover and non-specific reads.
- Correlation of microbial profiles with clinical metadata to evaluate reproducibility and relevance.
| Study element | Details reported | Health-system relevance |
|---|---|---|
| Cohort and samples | >9,000 patients; 11,735 samples; 22 cancer types | Supports generalizability and benchmarking across tumor types |
| Sequencing modality | Whole genome sequencing (WGS) | Aligns with expanding clinical WGS pipelines in oncology |
| Microbial profiling | Non-human reads analyzed after human DNA removal | Enables secondary insights without additional sampling |
| Diagnostic signal | Distinct signature only in colorectal tumors | Potential adjunct for diagnostic classification |
Clinical signals beyond the colon
The research suggests that microbial information embedded in WGS data can surface clinically relevant pathogens and prognostic associations in several contexts, even when a unique tumor-wide “fingerprint” is not observed.
- Pathogen detection within cancer workflows
- Higher-fidelity detection of oncogenic viruses such as HPV in oral cancers within sequencing data streams.
- Identification of rare but clinically important viruses, including HTLV-1, that may otherwise be missed in routine testing panels.
- Associations with outcomes in sarcomas
- Specific bacterial taxa linked with differences in survival, warranting prospective validation.
- Potential to refine risk stratification if associations hold in clinical trials.
“The study also points to broader clinical uses. In oral cancers, researchers found that certain viruses such as HPV (human papillomavirus) could be detected more accurately than with some current diagnostic tests.
They also identified rare but dangerous viruses, including Human T-Lymphotropic Virus-1 (HTLV-1), which can remain dormant in the body and later contribute to cancer development.
“We found that certain types of bacteria were associated with poorer survival rates in some cases of sarcoma. This might lead to additional research and treatment options for these types of cancer,” said Dr. Gihawi.
“One of the most exciting things we found was that in some sarcoma cases, the presence of specific bacteria was linked to better survival rates.
“This suggests that microbes might one day help doctors predict how well a patient will respond to treatment and open up new approaches to treatment,” he added.
Prof Daniel Brewer, from UEA’s Norwich Medical School, said: “This study highlights the growing clinical value of whole genome sequencing in identifying pathogenic organisms such as HTLV-1 and papillomavirus, which may otherwise go undetected.
“By revealing these hidden infections and providing insight into cancer prognosis — particularly in sarcomas — it demonstrates how genomic analysis is becoming an indispensable tool in precision medicine.
“The findings also suggest that oral cancer, in some cases, may be a close diagnostic consideration, further emphasizing the importance of comprehensive genomic profiling in clinical decision-making.”
What this could mean for health systems and payers
Because the microbial signal is extracted from data already being generated for cancer genomics, the study sits squarely in debates over how far routine sequencing should be used for secondary findings in public healthcare systems.
- Potential near-term applications
- Diagnostic adjunct: microbial profiles aiding tumor classification when pathology is ambiguous.
- Reflex pathogen screening: detection of oncogenic or treatment-relevant pathogens embedded in existing WGS pipelines.
- Risk stratification research: microbial associations informing prognostic models pending validation.
- Population and equity considerations
- Use of national sequencing datasets can reduce geographic variation in access if embedded within publicly funded programs.
- Representative sampling across ancestries and tumor subtypes remains essential to avoid biased models.
- Economic and operational implications
- Marginal-cost leverage: microbial profiling utilizes data already generated by WGS, limiting added laboratory burden.
- Bioinformatics capacity: requires validated pipelines, compute resources, and QA/QC for contamination control.
| Domain | Current baseline | Potential shift with WGS-embedded microbiome data | Implementation considerations |
|---|---|---|---|
| Diagnostic workflows | Histopathology and targeted molecular assays | Adjunct classification for colorectal tumors; reflex pathogen detection | Clinical validation; reporting standards; integration into tumor boards |
| Regulatory oversight | Accredited labs validate human variant calling | Expanded validation for non-human read analysis and contamination control | Method performance metrics; external proficiency testing |
| Reimbursement | Coverage focused on human genomic utility | Potential inclusion of pathogen findings and prognostic value | Evidence of clinical validity and utility for payer assessment |
| Data governance | Consent frameworks for genomic data | Explicit policies for incidental pathogen discovery and notification | Patient communication pathways; ethics review for secondary findings |
| Public-health linkage | Cancer registries and infection surveillance operate separately | Opportunities to flag oncogenic pathogens identified within tumor data | Secure data sharing; thresholds for public-health reporting |
Guardrails and open questions for policymakers and researchers
For regulators and public payers, the findings raise immediate questions about how to integrate microbial information into existing genomic governance frameworks, which were largely designed around human DNA.
- Analytical robustness
- Prospective validation across platforms and centers to confirm colorectal specificity.
- Standardized decontamination and reference databases to mitigate false positives.
- Clinical translation
- Defining when a microbial signature meaningfully changes diagnosis or management.
- Establishing actionability thresholds for reporting incidental pathogen findings.
- Workforce and infrastructure
- Bioinformatics training for clinical laboratories and molecular tumor boards.
- Interoperable reporting systems that handle both human and microbial results.
- Equity and access
- Ensuring sequencing access in underserved populations so benefits are not concentrated in a few centers.
- Monitoring performance across diverse demographic and tumor subgroups.
In the UK, initiatives such as Genomics England operate within the consent, data-use, and safety standards set out by the Data Protection Act 2018, meaning any move to treat microbial fingerprints as clinically actionable information will have to navigate existing rules on secondary use of genomic data and communication of incidental findings to patients.
Study collaboration and funding footprint
- Collaborators included multiple UK universities and institutes, an NHS foundation trust, and partners in Greece and the United States.
- Funding support came from the Big C Cancer Charity and Prostate Cancer UK.
- Use of national-scale datasets such as those generated by Genomics England illustrates how coordinated infrastructure can surface secondary insights without additional patient procedures.
The work also underscores how publicly funded sequencing programmes can generate policy-relevant evidence on future cancer diagnostics, long before bespoke microbiome tests reach the market.
The population-level lens
- Health outcomes
- Colorectal cancer remains a leading cause of cancer mortality; a robust microbial fingerprint could support earlier and more precise classification within existing diagnostic pathways.
- Microbe-outcome signals in sarcomas merit prospective trials before any clinical adoption.
- System capacity
- WGS adoption is growing in oncology, creating an opportunity to extract microbial insights at marginal cost.
- Scaling requires validated pipelines, quality standards, and cross-disciplinary expertise.
- Policy measures
- Clear guidance on validation, reporting, and follow-up for incidental pathogen findings within cancer genomes.
- Alignment between clinical laboratories, cancer programs, and public-health surveillance where oncogenic pathogens are identified.
- Population impacts
- Potential for improved diagnostic precision in colorectal cancer without new specimen collection.
- Opportunity to detect clinically significant infections embedded in oncology workflows, with appropriate safeguards.
For health ministries and cancer agencies, the central question now is whether microbial fingerprints uncovered in genomic data should simply inform research, or whether they will eventually be written into colorectal cancer pathways alongside colonoscopy, imaging, and molecular testing – with all the regulatory, reimbursement, and ethical decisions that follow.
