ACS Keeps Colorectal Screening at 45, Adds Limited Blood Test Option
An American Cancer Society guideline update keeps colorectal cancer screening starting at age 45 for average-risk adults and adds a blood-based option for people who decline or do not complete preferred screening tests.
The practical takeaway: on May 27, 2026, the American Cancer Society updated its colorectal cancer screening guideline. The starting age did not change for most average-risk adults, who should still begin screening at 45. What did change is that the group now includes a blood-based screening option for people who decline or do not complete preferred screening tests.
That does not mean colonoscopy has been replaced. The updated guidance still describes colonoscopy as the gold-standard screening test, and it says any positive result from a stool- or blood-based screening test should be followed by a colonoscopy, preferably within six months, to complete the screening process.
What changed in the 2026 guideline
The update, published in CA: A Cancer Journal for Clinicians, adds a blood-based test that looks for tumor DNA in blood and also includes newer at-home stool testing options. The American Cancer Society says the point is practical: more screening choices may help reach people who are eligible for testing but are not getting screened.
That gap is still large. In its release, the society said more than 20 million eligible adults in the United States are not up to date with colorectal cancer screening. For some people, barriers include bowel prep, time off work, transportation, or discomfort with handling a stool test at home.
What did not change
The main message remains familiar. For most people at average risk, colorectal cancer screening should still start at 45. Screening is meant for people who do not have symptoms. Its purpose is to find cancer early or detect precancerous polyps before they turn into cancer.
CDC continues to say that several screening methods are available, including tests that can be done at home. It also notes that if a stool test, flexible sigmoidoscopy, or CT colonography is positive or abnormal, a colonoscopy is needed to complete the screening process.
Why the new blood test comes with tradeoffs
The new blood-test option may sound simpler, but the guideline does not treat it as equal to established screening approaches. The American Cancer Society says blood-based screening tests showed lower sensitivity than established stool-based tests for advanced precancerous lesions and for stage I cancers. In plain language, that means a blood test may miss some of the earliest or most preventable findings that other options are better at catching.
FDA approved the Shield blood test in July 2024 for adults 45 and older who have an average risk of colorectal cancer and need screening. FDA also says Shield is not a replacement for diagnostic colonoscopy or for surveillance colonoscopy in people at high risk. People with a positive result are advised to have a diagnostic colonoscopy, and people with a negative result should keep participating in routine colorectal cancer screening because a negative test does not guarantee that cancer is absent.
It is also important to keep the evidence in perspective. This was a guideline update, not a new randomized trial proving that blood-based screening improves real-world outcomes more than other screening options. The guideline authors say future updates will depend on how these newer tests perform in real-world use, including participation, follow-up, and clinical outcomes.
Who may need a different plan
Average-risk guidance does not apply to everyone. CDC says people with inflammatory bowel disease, a personal or family history of colorectal cancer or polyps, or inherited syndromes such as Lynch syndrome or familial adenomatous polyposis may need earlier screening, different tests, or more frequent follow-up.
Screening also is not the same as evaluating symptoms. CDC says symptoms such as blood in or on the stool, a lasting change in bowel habits, abdominal pain that does not go away, or unexplained weight loss should be checked by a clinician rather than folded into a routine screening plan. If you have those symptoms, seek prompt medical evaluation instead of relying on a screening test alone.
What readers can do now
If you are 45 or older and not up to date on screening, a useful next step is to check when you last had a colorectal cancer test and ask which option fits your risk, preferences, and access. For some people, that may still be colonoscopy. For others, a stool-based test at home may be more realistic. The new blood-based option may help some people who would otherwise do nothing, but it is not the strongest option for every situation.
It is also reasonable to ask practical questions before scheduling. Coverage and out-of-pocket costs can vary by plan and by what follow-up care is needed, so patients should confirm what a specific screening test will cost and whether a follow-up colonoscopy would also be covered if a result is positive.
The bottom line is simple: the best screening test is still the one that gets completed, but the newest blood-test option comes with important limits. For some people, this update expands choice. It does not remove the need to understand what each test can and cannot do.
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.
