New Colorectal Cancer Blood Test Detects Precancerous Colon Lesions

A new colorectal cancer blood test has produced unusually encouraging results because it did something many blood-based screening approaches still struggle to do: detect advanced adenomas before they become cancer. In the multicentre DENEB study, the experimental assay detected 81% of advanced adenomas and 92% of stage I to III colorectal cancers in its testing cohort. Those findings do not mean the test is ready to replace colonoscopy, but they suggest blood-based screening may eventually become better at preventing colorectal cancer rather than only finding cancers that have already developed.

The study, published in The Lancet Gastroenterology & Hepatology and indexed by PubMed, used patterns of microRNAs circulating in blood to distinguish people with colorectal cancer or advanced adenomas from people without advanced disease. Researchers combined laboratory measurements with machine-learning models and concluded that the colorectal cancer blood test should now move into much larger prospective studies before its role in routine screening can be established.

That distinction is essential. The colorectal cancer blood test is experimental. It is not the same as blood tests already approved for colorectal cancer screening in the United States, and a positive result would still need to be followed by colonoscopy. The importance of this research lies in its ability to identify precancerous lesions at a substantially higher rate than blood screening has generally managed so far.

The New Study at a Glance

Measure	DENEB study result
Sensitivity for colorectal cancer, any stage	91%
Sensitivity for stage I–III colorectal cancer	92%
Sensitivity for advanced adenomas	81%
Specificity for advanced neoplasia	85%
Specificity among people with negative colonoscopy	83%
Biomarkers measured	19 cell-free and 20 exosomal microRNAs
Method	RT-qPCR plus XGBoost machine learning
Locked testing cohort	230 participants
Current status	Experimental, larger prospective validation needed

These figures come from the peer-reviewed DENEB study. Sensitivity describes how often a test correctly identifies people who have the condition being sought, while specificity describes how often it correctly identifies people who do not have the relevant disease or lesion.

Why Finding Precancerous Lesions Changes the Screening Equation

The most important feature of this colorectal cancer blood test is not simply that it detected cancer. It detected advanced adenomas.

Many colorectal cancers begin as abnormal growths in the lining of the colon or rectum. These growths are commonly called polyps. Not every polyp becomes cancerous, but advanced adenomas have characteristics associated with a greater risk of progression toward cancer. Detecting and removing them is therefore an important part of preventing colorectal cancer.

Colonoscopy can both find and remove suspicious polyps during the same procedure. This is one reason colonoscopy has a preventive advantage over tests designed mainly to detect established tumors. If an advanced adenoma is removed before malignant transformation occurs, a future cancer may never develop.

The challenge for blood-based screening has been detecting these earlier lesions reliably. Blood tests are attractive because drawing blood is familiar, quick and does not require bowel preparation. Yet the American Cancer Society currently says blood-based screening is not a preferred option because available tests are less effective than preferred stool-based and visual methods at detecting precancerous growths.

That is where the colorectal cancer blood test studied in DENEB becomes interesting. An 81% sensitivity for advanced adenomas, if reproduced in much larger population studies, could narrow one of the biggest gaps between blood screening and established approaches.

It could shift the question from whether a blood test can detect colorectal cancer to whether a blood test can help prevent it by identifying the people who need colonoscopy while dangerous lesions are still precancerous.

The preventive value is particularly important because colorectal cancer remains a major health burden. The National Cancer Institute’s SEER program estimates 158,850 new U.S. colorectal cancer cases and 55,230 deaths in 2026. Five-year relative survival for localized colorectal cancer is about 91%, showing why earlier detection matters.

The News Ink has also covered the human consequences of later diagnosis through former quarterback Stephen Garcia, who publicly discussed his stage 4 colorectal cancer diagnosis and urged greater attention to early screening.

How the Colorectal Cancer Blood Test Works

The science behind the colorectal cancer blood test is more complex than a routine blood count.

Researchers in the DENEB study focused on microRNAs, usually shortened to miRNAs. These are small RNA molecules involved in regulating gene activity. Disease processes can alter which microRNAs are circulating in blood and how strongly they are expressed.

The researchers first searched for candidate microRNAs that were overexpressed in people with colorectal cancer and adenomas. Samples from discovery cohorts were combined with additional datasets that acted as a reproducibility filter before the researchers advanced the strongest biomarkers into the clinical model.

The final colorectal cancer blood test interrogated the expression of 19 cell-free and 20 exosomal microRNAs.

Cell-free molecules circulate outside intact cells. Exosomes are tiny membrane-bound particles released by cells that can carry molecular material, including RNA. Because tumors and precancerous tissue can change these molecular signals, scientists are investigating whether they can serve as a form of liquid biopsy.

The assay used reverse transcription quantitative polymerase chain reaction, or RT-qPCR, to measure the selected microRNAs. Researchers then used XGBoost machine learning to construct separate models for colorectal cancer and advanced adenomas.

Importantly, those models and their diagnostic thresholds were locked before they were tested on the independent clinical cohort. This reduces the risk of simply adjusting a model until it performs well on the same samples used to develop it.

The DENEB project involved several stages. Two discovery cohorts contained 274 and 307 participants. A clinical training cohort included 535 people, while a separate testing cohort contained 230. Additional datasets from Japan, Spain and China contributed to biomarker discovery and validation.

The study was also outcome-enriched, meaning researchers deliberately included enough people with colorectal cancer and advanced adenomas to assess how effectively the assay recognized those conditions.

That is useful for developing a test, but it creates an important limitation. Performance in an enriched research cohort does not automatically tell us exactly how the colorectal cancer blood test would perform when used among millions of average-risk adults, most of whom do not have cancer or advanced adenomas.

Why the 81% Advanced Adenoma Result Stands Out

The headline result for the colorectal cancer blood test is its 81% sensitivity for advanced adenomas.

In the testing cohort, the assay detected 91% of colorectal cancers across all stages and 92% of stage I, II and III cancers. It achieved 85% specificity for advanced neoplasia and 83% specificity among participants whose colonoscopies were negative.

Those are promising numbers, but the advanced adenoma result separates this research from much of the existing conversation around blood-based colorectal screening.

The FDA approved Shield as the first blood test for primary colorectal cancer screening in average-risk adults in 2024. In the pivotal study summarized by the National Cancer Institute, Shield’s cell-free DNA approach detected 83.1% of colorectal cancers but only 13.2% of advanced precancerous lesions.

That does not prove the new colorectal cancer blood test is already better than Shield.

The studies involved different designs, populations, biomarkers and methods. Comparing percentages from separate trials as though they came from a head-to-head study would be misleading.

What the comparison does illustrate is the scientific problem researchers are trying to solve.

A test that detects established cancers but misses most advanced precancerous lesions may improve cancer detection, but its ability to prevent cancer is more limited. A colorectal cancer blood test that consistently detects advanced adenomas could potentially offer a more preventive form of screening.

Researchers also reported that the DENEB assay could distinguish between low-risk adenomas, high-risk adenomas and cancers. In theory, that could eventually help clinicians prioritize which people need the most urgent colonoscopy. Reuters noted that such risk stratification is one possible future use of the technology.

A future validated system might help distinguish:

• people at high risk who need prompt diagnostic colonoscopy;
• people likely to have advanced adenomas that should be removed;
• people with lower-risk findings who need different follow-up;
• and people unlikely to have advanced colorectal neoplasia.

That is a potential future application, not current medical guidance.

There is also an important weakness. Reuters reported that the colorectal cancer blood test was less successful at identifying some sessile, or flatter, areas of concern. Researchers said larger studies are needed to investigate the problem.

Colonoscopy Still Has an Advantage No Blood Test Can Match

Excitement around a colorectal cancer blood test can easily create the impression that colonoscopy is about to become unnecessary. That is not what current evidence or medical guidelines say.

Colonoscopy remains one of the preferred screening methods because a clinician can inspect the colon directly, biopsy suspicious tissue and remove many precancerous polyps during the procedure.

A blood test cannot remove an advanced adenoma.

If a colorectal cancer blood test produces an abnormal result, the patient still needs colonoscopy to establish what is present and, where appropriate, remove the lesion. The American Cancer Society recommends timely colonoscopy after a positive blood-based or stool-based screening result. Its 2026 update says this should preferably occur within six months.

The ACS updated its colorectal cancer screening guidance in May 2026. Average-risk adults are still advised to begin regular screening at age 45 and continue through age 75 if they are in good health and have a life expectancy of more than 10 years. Decisions from ages 76 to 85 should be individualized.

Preferred options currently include:

• annual fecal immunochemical testing, or FIT;
• other recommended stool-based molecular tests;
• colonoscopy every 10 years for appropriate average-risk adults;
• CT colonography;
• and sigmoidoscopy.

Blood-based testing is included as another screening option, but the ACS currently recommends it mainly for people who decline or do not complete the preferred tests.

The reasoning is practical. Even an excellent screening method provides no benefit if a person never completes it. A simple blood draw may appeal to people who avoid bowel preparation, stool collection or invasive procedures.

The ACS estimates that more than 20 million Americans who are eligible for colorectal cancer screening are not up to date. Expanding the range of acceptable screening methods could therefore bring more people into the screening system.

But convenience should not be confused with completeness. The experimental colorectal cancer blood test still needs prospective validation, and colonoscopy would remain crucial after a positive result.

Cancer Research Is Moving Earlier in the Disease Process

The DENEB findings are part of a broader change in cancer research. Scientists increasingly want to identify the molecular signals of disease before tumors become large, advanced or metastatic.

Researchers are studying circulating tumor DNA, proteins, methylation changes, microRNAs, exosomes and combinations of biomarkers interpreted with machine learning.

The colorectal cancer blood test is one example of this wider liquid-biopsy movement.

For colorectal cancer, precancer detection is especially valuable because many cancers develop through a progression in which abnormal tissue may be found and removed before it becomes invasive.

Scientists are also studying the biological mechanisms that may push normal colon tissue toward malignancy. The News Ink recently covered research involving a Bacteroides fragilis toxin and colon cancer, which examined another part of the complex process behind colorectal tumor development.

Similar research is underway across oncology. Work on a hidden weakness in pancreatic cancer is exploring possible treatment vulnerabilities, while advances in cancer immunotherapy are trying to improve treatment after cancer is established.

The colorectal cancer blood test occupies an earlier point in that spectrum: identifying dangerous changes soon enough that intervention might prevent an invasive cancer from developing.

What the Study Does Not Prove

Promising diagnostic research can generate headlines faster than the evidence justifies.

The DENEB study does not prove that the colorectal cancer blood test reduces cancer deaths. It does not prove that population-wide use would prevent more cancers than existing screening strategies. It does not establish how frequently people should be tested, what a commercial version would cost, or how it would perform across every population.

It also does not mean people should cancel scheduled colonoscopies.

Several limitations deserve attention.

First, the final testing cohort included 230 participants. That provides meaningful independent validation but is far smaller than the population needed to establish real-world screening effectiveness.

Second, the design was outcome-enriched and case-controlled. Large prospective screening trials among unselected average-risk adults are still required. The investigators themselves concluded that the next stage should be larger-scale prospective evaluation.

Third, wider demographic validation matters. The study incorporated international cohorts and datasets, but future research will need to confirm that performance remains strong across diverse racial, ethnic and healthcare populations.

Fourth, false positives remain an issue. Specificity was 85% for advanced neoplasia. In a general screening population where most people do not have advanced lesions, false-positive results could send substantial numbers of people to follow-up colonoscopy.

Fifth, flat lesions require more study. Reuters reported lower performance with some sessile lesions, an important limitation because not all dangerous colorectal lesions form easily recognized raised polyps.

Screening also depends on the full care pathway. A positive blood result only becomes preventive if the person receives timely follow-up, colonoscopy, biopsy where needed and removal of the lesion.

What Happens Next for the Colorectal Cancer Blood Test

Researchers concluded that the colorectal cancer blood test has produced enough evidence to justify large prospective studies.

A strong next-stage trial would ideally enroll thousands of people actually undergoing routine screening, collect blood before their disease status is known, compare the test with colonoscopy and determine how well it identifies cancers and advanced precancerous lesions under real-world conditions.

Researchers will also need answers to practical questions:

• Does performance remain consistent across age, sex and ethnicity?
• Can the assay reliably detect flat and serrated lesions?
• What threshold gives the best balance between sensitivity and false positives?
• How frequently should people be tested?
• How does it compare directly with FIT, stool DNA or RNA tests and existing blood tests?
• Does offering blood screening increase overall screening participation?
• Do people with positive tests complete follow-up colonoscopy?
• Would population-wide use be cost-effective?
• Most importantly, does it ultimately reduce colorectal cancer incidence and mortality?

Until those questions are answered, the colorectal cancer blood test should be regarded as a promising research development rather than a new standard of care.

Medical screening technologies have to prove more than laboratory accuracy. They need to work consistently across ordinary patients, healthcare systems and real-world follow-up pathways.

Frequently Asked Questions

Is the new colorectal cancer blood test available now?

The DENEB colorectal cancer blood test described in the 2026 study is experimental and is not currently a routine commercial screening test. Researchers say larger prospective studies are needed before its clinical role can be established.

How accurate was the test for precancerous lesions?

In the independent testing cohort, the colorectal cancer blood test detected 81% of advanced adenomas. It detected 91% of colorectal cancers overall and 92% of stage I to III cancers.

Does this mean people can avoid colonoscopy?

No. Colonoscopy remains a preferred screening method and is still required after an abnormal blood-based or stool-based screening result. Colonoscopy can also remove precancerous polyps during the procedure, something a blood test cannot do.

At what age should colorectal cancer screening begin?

The American Cancer Society recommends that average-risk adults begin regular colorectal cancer screening at age 45. People at increased risk because of family history, hereditary syndromes, inflammatory bowel disease or other factors may need a different schedule.

Are there already blood tests for colorectal cancer screening?

Yes. Blood-based colorectal screening options already exist in the United States. However, the American Cancer Society currently categorizes blood-based testing as an alternative rather than a preferred option because existing blood tests are generally less effective at detecting precancerous growths.

Conclusion

The new colorectal cancer blood test is noteworthy because it targets the point where screening may be able to do the most good: before cancer develops.

In the DENEB study, the experimental assay detected 81% of advanced adenomas, 91% of colorectal cancers overall and 92% of stage I to III cancers. It did so by analyzing patterns across 19 cell-free and 20 exosomal microRNAs and processing those signals through machine-learning models.

Those numbers are promising, but they are not a reason to abandon existing screening. The colorectal cancer blood test still needs large prospective trials, stronger evidence on flat lesions, real-world data on false positives and confirmation that its performance can be reproduced across broad screening populations.

For now, colonoscopy and established stool-based tests remain central to colorectal cancer prevention, while blood screening offers another option for some people under current U.S. guidance.

If future studies confirm the DENEB findings, however, the colorectal cancer blood test could help address one of cancer prevention’s biggest challenges: getting more people screened while still identifying dangerous precancerous lesions early enough to remove them.

This article is for general information only. It is not a substitute for professional medical advice, diagnosis or treatment.

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