Many people skip colonoscopies as a test for colorectal cancer, and the American Cancer Society has now updated its screening guidelines, expanding the number of methods to include a simple blood test – hoping to encourage more people over 45, reports The Washington Post.
Colorectal cancer is usually preventable and treatable when caught early, but about a third of adults who are eligible for these screenings are not up to date, according to the American Cancer Society.
Colorectal cancer is the third most common cancer diagnosis in the US, estimated to cause nearly 160 000 new cancer diagnoses and 55 0000 deaths each year. It is the leading cause of cancer death in adults under 50.
The simplicity of a blood test comes with a major caveat that will require nuanced discussions between doctors and patients. Shield, a blood-based colorectal cancer test that detects fragments of tumour DNA, was approved by regulators in 2024. But the test, developed by Guardant Health, misses more precancerous polyps and early-stage cancers than other methods.
The new guidelines, published in CA: A Cancer Journal for Physicians, recommends it only for people who won’t otherwise get screened.
A colonoscopy is the gold standard for screening and is recommended every 10 years beginning at 45 until age 75. The guidelines also recommend at-home stool testing, which detects blood or genetic markers of colorectal cancer.
The blood test is now a third option, though oncologists stressed it is not the preferred option.
“The most effective screening test is the one that the patient completes,” said William Dahut, chief scientific officer of the American Cancer Society. “If the patient knows that it’s not as good at picking up Stage 1 cancers and pre-cancer, but they are not going to do those other tests, they should go and do it.”
In a large clinical trial published in The New England Journal of Medicine, the Shield test from Guardant Health detected 83% case of colon cancer, but only 13% of advanced precancerous lesions.
Matt Kalady, director of the James Colorectal Cancer Centre at Ohio State University Comprehensive Cancer Centre, said that adding a blood-based screening test is “fantastic”, but that because they are not as sensitive or effective as colonoscopy or stool-based tests, they “should only be used for individuals who decline or cannot do the standard screening tests”.
Ronald Driggers, a 68-year-old retired crane operator from Georgia, is one of those who could not be persuaded. Driggers describes himself as a “procrastinator when it comes to my healthcare”. His doctor had been bugging him for years to get a colonoscopy because of his age, but Driggers declined.
He was offered the stool-based test, and three were sent to his home. He threw them out, disgusted by the idea of the sample collection and preparation.
Finally, in late 2024, his doctor mentioned the blood test, and Driggers said okay. The test came back positive, which was the push he needed to finally get a colonoscopy. Driggers had stage 3 colorectal cancer, which had spread to his lymph nodes.
“I would have gone on and on and on till I developed symptoms,” Driggers said. “I would have just rolled along with my stupid self till it did move to an organ – and cancer is like rust, it continues to spread until it just eats you up.”
Driggers underwent 28 rounds of chemotherapy and radiation treatments and still has numbness in his feet and hands. But he plans to live a long time – and goes back for follow-up colonoscopies every three months now.
Scott Ramsey, a physician and cancer researcher at the Fred Hutch Cancer Centre in Seattle, said he agreed the most important thing is people get screened. But he worries about the test’s inferior performance in finding advanced adenomas, precancerous polyps.
“Now we have three different options we can talk patients through, and it’s getting pretty complicated,” Ramsey said. “On one hand, I’m glad there’s another option to present to patients, and on the other hand the conversation is even more complicated.”
He said he was also concerned that people who opted for either a stool-based test or a blood test and get a positive result may not do the essential follow-up – a colonoscopy.
Study details
Colorectal cancer screening: An update to the American Cancer Society guideline, 2026
Andrew Wolf, Richard Hoffman, Louise Walter et al.
Published in The New England Journal of Medicine on 27 May 2026
ABSTRACT
Colorectal cancer (CRC) is a leading cause of cancer incidence and mortality in the United States, with rates recently increasing among adults younger than 65 years. In 2018, the American Cancer Society (ACS) lowered the recommended age to initiate screening for average-risk adults to age 45. Since then, new molecular-based screening tests—a multitarget stool RNA test (mt-sRNA), a next-generation mt-sDNA test, and a blood-based cell-free DNA assay—have received regulatory approval for CRC screening. For this update, the ACS Guideline Development Group commissioned a targeted, systematic evidence review evaluating diagnostic performance and published modelling studies to judge the potential impact of these tests on CRC incidence and mortality. The ACS reaffirms the recommendation that average-risk adults should initiate CRC screening at 45 and continue to age 75 for those with a life expectancy greater than 10 years. Consistent with prior guidelines, the ACS emphasises that offering multiple, recommended screening options supports informed patient choice and may improve participation, because the most effective screening test is the one that the patient completes. The next-generation mt-sDNA test, which is an updated version of an already recommended mt-sDNA test, and the mt-sRNA test demonstrated high sensitivity for CRC and moderate sensitivity for advanced precancerous lesions and are recommended, along with annual high-sensitivity faecal immunochemical and high-sensitivity guaiac-based faecal occult blood tests, as preferred stool-based screening options at 3-year intervals. Compared with established stool-based tests, blood-based tests demonstrated lower sensitivity for both advanced precancerous lesions and stage I cancers, with modelling studies predicting less effectiveness in reducing CRC incidence and mortality. At this time, blood-based tests should be recommended only to individuals who decline or do not complete preferred screening tests. Ongoing evaluation of adherence, real-world implementation, and clinical outcomes will inform future updates for these new tests. For screening to be effective, a positive result on any non-colonoscopy screening test requires timely follow-up with colonoscopy, preferably within 6 months, to complete the screening process.
See more from MedicalBrief archives:
Updated US guidelines for colorectal cancer screenings
ACS recommends earlier colorectal cancer screening