Can a New Colon-Cancer Blood Test Replace Colonoscopy? What ACS Says

For most people, no.

On May 27, 2026, the American Cancer Society updated its colorectal cancer screening guideline to add a blood-based test as an option for some average-risk adults. But colonoscopy and stool-based tests are still the preferred choices, and a positive blood test still needs a timely follow-up colonoscopy.

That means a blood test may be better than skipping screening altogether. It does not mean colonoscopy is outdated, or that a blood test is the right choice for everyone.

What changed in the 2026 ACS update

The main age advice did not change. The American Cancer Society says average-risk adults should start colorectal cancer screening at age 45 and continue through age 75 if life expectancy is more than 10 years. For ages 76 to 85, screening should be an individual decision with a clinician. Routine screening is generally not continued after age 85.

The new part is that blood-based screening tests are now included among recommended options for average-risk adults. Even so, the guideline says they are not preferred at this time.

Why colonoscopy and stool tests still matter

The preferred screening group still includes stool-based tests and direct visual exams, most commonly colonoscopy. The reason blood tests are not preferred is performance: the American Cancer Society says today’s blood-based tests are less likely to find precancerous growths and stage I colorectal cancer.

That matters because screening is not only about finding cancer. It is also about finding polyps early enough to remove them before they turn into cancer.

Colonoscopy also does something a blood test cannot do on its own: it lets a specialist look directly inside the colon and remove many polyps during the same procedure. A blood test cannot remove a polyp, and it cannot confirm an abnormal result. If the blood test is positive, you still need colonoscopy.

What the blood-test study found

In a large cross-sectional study published in the New England Journal of Medicine and indexed in PubMed, a cell-free DNA blood test detected about 83% of colorectal cancers overall. But it detected only about 13% of advanced precancerous lesions. That helps explain why the American Cancer Society added blood testing as an option but did not move it into the preferred group.

The study is important, but it has limits. It measured how well the test performed against colonoscopy at one point in time. It did not by itself prove that using the blood test will prevent as many cancers or deaths as preferred screening methods. A negative blood test also does not guarantee that cancer is not present.

Who this option may fit

This update is mainly relevant for adults at average risk who do not have symptoms and who might otherwise skip screening.

Ages 45 to 75: screening is generally recommended.
Ages 76 to 85: the decision should be individualized.
Over 85: routine screening is generally not continued.

Average risk usually means you do not have a personal history of colorectal cancer or adenomatous polyps, inflammatory bowel disease, or a hereditary syndrome or family-history pattern that changes screening needs. If you are not sure whether that describes you, ask before choosing a test.

When a blood test should not be treated as enough

Screening is for people who feel well and do not have warning signs. The CDC notes that colorectal cancer may not cause symptoms at first, which is why routine screening matters. But once symptoms are present, the issue is no longer just screening.

Do not rely on a screening blood test alone if you have symptoms such as:

blood in the stool
a persistent change in bowel habits
ongoing abdominal pain
unexplained weight loss

If you have severe abdominal pain, heavy rectal bleeding, fainting, or feel acutely ill, seek urgent medical care right away.

What Medicare coverage means in practice

For readers on Medicare, CMS says an eligible blood-based biomarker colorectal screening test is covered once every 3 years for asymptomatic, average-risk beneficiaries ages 45 to 85, when other program criteria are met.

That does not automatically mean every private or employer plan will handle coverage the same way. The ACS guideline itself does not set insurance benefits, and screening coverage, follow-up billing, and network rules can vary by plan. It is worth checking before you schedule a test.

Questions to ask before choosing a blood test

Am I truly average risk, or do I need a different screening plan?
If my result is positive, who will arrange the colonoscopy?
Will my insurance cover both the screening test and any follow-up?
Would I be more comfortable with a stool test or colonoscopy instead?

The practical takeaway

The 2026 American Cancer Society update does not make colonoscopy obsolete. It adds another screening option for average-risk adults, especially those who may otherwise go unscreened.

For many people, the best next step is to talk with a clinician about which test you are most likely to complete and which one matches your risk. If you choose a non-colonoscopy option, go in knowing that a positive result still means colonoscopy is the next step.

Sources

Editorial note: Weence articles are researched from cited public-health, medical, regulatory, journal, and reputable news sources and may be drafted with AI assistance. They are checked for source support, clarity, and safety guardrails before publication.

This article is for general informational purposes only and is not medical advice. Research findings can be early or incomplete, and health guidance can change. Always talk with a qualified healthcare professional about personal symptoms, diagnosis, medications, vaccines, screenings, or treatment decisions. If you think you may have a medical emergency, call emergency services right away.