Experimental Blood Test Catches 81% of High-Risk Colorectal Polyps in International Trial

A new experimental blood test for colorectal cancer detected 81 percent of advanced precancerous polyps and 92 percent of stage I through III colorectal cancers in a multisite diagnostic study, according to findings published August 10 in The Lancet Gastroenterology & Hepatology. The result matters because catching the polyp, not just the cancer it can become, is what actually bends the mortality curve.

The test, called DENEB, works by measuring the expression of 39 microRNAs, a mix of cell-free and exosomal signals, drawn from a standard blood sample. Researchers ran it through the Early Detection Research Network's phase I-III framework, using separate cohorts for discovery, training, and validation so the numbers weren't inflated by overlap. Participants came from colorectal screening programs in China, Japan, and Spain, and colonoscopy served as the reference standard throughout.

The headline sensitivity figure for advanced adenomas, 81 percent, is the one gastroenterologists will focus on. Current blood-based tests approved for colorectal screening have been considerably better at finding established cancers than the precancerous lesions that, if removed, prevent cancer from forming at all. The American Cancer Society's updated 2026 screening guideline specifically notes that existing blood tests have lower sensitivity for advanced precancerous lesions than established stool-based approaches, according to reporting by Research Today that reviewed the Lancet findings.

Specificity for advanced neoplasia was 85 percent in the validation cohort, according to the Lancet paper. That means roughly 15 percent of people without advanced disease would get a positive result, and every positive blood test still requires a follow-up colonoscopy to confirm it. That's not a footnote. It's the part that determines whether a test like this adds net value to a screening program or just adds colonoscopy volume.

Colorectal cancer is the third most common cancer and second deadliest in the United States. More than a third of people eligible for screening aren't up to date, according to prior NEJM data on cfDNA blood testing. A blood draw is easier to say yes to than a bowel prep. That's the argument for investing in tests like DENEB: if higher participation offsets the imperfect sensitivity, the population-level math might still work out.

The study design does carry limitations worth naming. It was case-controlled and outcome-enriched, meaning the cohort included proportionally more people with disease than a typical screening population would. That tends to inflate sensitivity estimates when you try to project them onto the general public. Researchers and clinicians who use it for screening decisions will be working with real-world performance that may look different from these trial numbers.

JAMA returned to the broader question of where blood-based colorectal screening fits on August 14, the same week Healthline reported on the DENEB findings. The American Cancer Society currently recommends blood-based tests specifically for people who decline or don't complete preferred methods, a position that reflects where the evidence actually sits, not where the marketing tends to land.

DENEB is still experimental. It isn't approved for routine screening, and the Lancet authors note that additional research is needed before it gets there. For patients, the practical message for now is unchanged: if you're due for colorectal cancer screening, talk to your primary care provider or gastroenterologist about the option that fits your situation. A blood test you'll actually do outperforms a colonoscopy you keep postponing, but the goal is still getting screened, not waiting for the perfect test.

Sources cited:
- The Lancet Gastroenterology & Hepatology (https://www.thelancet.com/journals/langas/article/PIIS2468-1253(26)00180-9/abstract)
- Research Today (https://researchtoday.co.za/blood-test-detects-81-of-high-risk-colorectal-polyps-in-international-study/)
- Healthline (https://alto.gab.com/feed/healthline-news/item/389333)
- PubMed / NCBI (https://pubmed.ncbi.nlm.nih.gov/42575119/)