Colorectal cancer has long been one of the most preventable yet deadly cancers in the United States. For years, doctors have emphasized the importance of screening because catching this cancer early can dramatically improve survival. Now, the American Cancer Society (ACS) has updated its guidelines to include a new tool in the fight against colorectal cancer: blood based screening tests. This shift is meant to help reach the millions of Americans who are still not getting screened, even though early detection can save lives.
These new guidelines do not replace colonoscopy or stool based tests, which remain the preferred and most effective options. Instead, the ACS hopes that adding blood tests will make screening more accessible for people who avoid traditional methods. Understanding what this change means, how the tests work, and who they are meant for can help more people take the first step toward protecting their health.
Why Screening Matters More Than Ever
Colorectal cancer is one of the few cancers that can often be prevented entirely if precancerous polyps are found and removed early. When caught at an early stage, the five year survival rate is more than 90 percent in the United States. Yet despite this, about one in three adults who are eligible for screening have never been tested, which amounts to more than 20 million people.
At the same time, colorectal cancer is becoming more common in younger adults. It is now the top cancer killer of adults under 50. This troubling trend has pushed experts to expand screening options and reduce barriers that keep people from getting tested.
What The Updated ACS Guidelines Say
The ACS reaffirmed that adults at average risk should begin screening at age 45 and continue through age 75 if they have a life expectancy of at least 10 years. Screening between ages 76 and 85 should be based on personal health and preferences, and screening is not recommended after age 85.
The new guidelines continue to emphasize colonoscopy and stool based tests as the preferred methods. These include:
- Colonoscopy every 10 years
- CT colonography every 5 years
- Sigmoidoscopy every 5 years
- Highly sensitive stool tests such as FIT or gFOBT every year
- Multi targeted stool DNA or RNA tests every 3 years
However, for the first time, the ACS has added blood based tests as an option for people who are unwilling or unable to complete stool tests or colonoscopy. These blood tests are not considered preferred because they are less effective at detecting early stage cancer or precancerous polyps. But they are still better than not being screened at all.
How The New Blood Tests Work
The newly recommended blood test, called Shield, detects fragments of tumor DNA circulating in the bloodstream. These fragments are shed by cancer cells, and the test looks for specific patterns that suggest colorectal cancer may be present. Shield was approved by the FDA in 2024.
Studies show that the Shield test is about 83 percent effective at detecting colorectal cancers. However, it is significantly less effective at finding early stage cancers or precancerous polyps, which do not release much DNA into the blood. This means the test is not as strong at preventing cancer as colonoscopy or stool based tests.
Still, experts say that for people who refuse other screening methods, a blood test is far better than skipping screening entirely. As Dr. Andrew Wolf, who helped lead the guideline update, explained, the most effective test is the one a patient will actually complete.
Why The ACS Added Blood Tests Now
The ACS hopes that expanding the list of acceptable screening options will help close the screening gap. Many people avoid colonoscopy because of the preparation, sedation, or discomfort. Others dislike stool based tests. By offering more choices, the ACS aims to reach people who might otherwise never get screened.
Dr. Robert Smith, senior vice president for early cancer detection science at the ACS, emphasized that colorectal cancer should be viewed as both preventable and treatable. He noted that offering more tools can help catch more cancers at earlier stages, when treatment is most effective.
The ACS also recognizes that screening rates have remained stubbornly low. About a third of Americans are not up to date on screening, and adding a simple blood draw could dramatically increase participation.
What Blood Tests Can And Cannot Do
Blood based screening tests offer convenience, but they come with important limitations. Understanding these can help people make informed decisions.
What They Can Do
- Detect DNA fragments shed by colorectal tumors
- Identify many cancers that might otherwise go unnoticed
- Provide a simple option for people who refuse colonoscopy or stool tests
- Increase overall screening rates by lowering barriers to participation
What They Cannot Do
- Detect most precancerous polyps
- Reliably find early stage cancers
- Replace colonoscopy as the gold standard
- Eliminate the need for follow up testing if results are positive
If a blood test comes back positive, the ACS stresses that a colonoscopy should be performed within six months. This is the only way to confirm the result and remove any polyps that could turn into cancer.
How Blood Tests Compare To Other Screening Options
Below is a simple comparison to help clarify how blood tests fit into the broader screening landscape.
| Screening Method | How It Works | How Often | Strengths | Limitations |
| Colonoscopy | Visual exam of the colon using a flexible tube | Every 10 years | Finds and removes polyps, best at detecting early cancer | Requires prep, sedation, time off |
| Stool Tests (FIT, gFOBT) | Detect hidden blood in stool | Every year | Non invasive, inexpensive | Must be done yearly, follow up colonoscopy if positive |
| Stool DNA or RNA Tests | Detect DNA or RNA markers in stool | Every 3 years | More sensitive than basic stool tests | Still requires stool sample, follow up colonoscopy if positive |
| Blood Test (Shield) | Detects tumor DNA in blood | Every year | Simple blood draw, good for people who refuse other tests | Less effective at detecting early cancer or polyps, follow up colonoscopy required if positive |
This table reflects the ACS guidance that blood tests should only be used when a person is unwilling to undergo stool based or visual exams. They are not preferred but are still considered acceptable.
Insurance Coverage And Cost Questions
One important detail is that insurance coverage for blood based screening tests is not guaranteed. The U.S. Preventive Services Task Force (USPSTF) has not yet updated its recommendations to include these tests. Insurance companies typically follow USPSTF guidelines when deciding what to cover at no cost to patients.
The Shield test currently costs about 895 dollars out of pocket. Until the USPSTF updates its recommendations, patients may need to pay for the test themselves.
The USPSTF usually updates its colorectal cancer screening guidelines every five years, and an update is expected in 2026. Experts hope that blood tests will be included, but nothing is certain yet.
Why Younger Adults Should Pay Attention
Colorectal cancer is no longer a disease that primarily affects older adults. Rates among people under 50 have been rising for years. Between 2013 and 2022, colorectal cancer rates increased 3 percent per year in people under 50. It is now the leading cause of cancer death in men under 50 and the second leading cause in women under 50.
This shift is one reason the ACS lowered the recommended screening age from 50 to 45 back in 2018. The new guidelines continue to emphasize the importance of starting screening earlier, especially as more young adults are being diagnosed.
What This Means For You
The most important message from the updated ACS guidelines is simple: get screened. Whether you choose a colonoscopy, a stool based test, or a blood test, taking action is what matters most.
If you are 45 or older and have not been screened, now is the time to talk to your doctor. If you have been avoiding screening because of discomfort, embarrassment, or inconvenience, the new blood test option may help you take that first step.
Doctors emphasize that no single test is perfect, and each has strengths and weaknesses. But the biggest risk is doing nothing at all. As the ACS notes, the best screening test is the one you will actually complete.
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Sources (3)
- American Cancer Society – Colorectal Cancer Guideline
https://www.cancer.org/cancer/types/colon-rectal-cancer/detection-diagnosis-staging/acs-recommendations.html - American Cancer Society – Colorectal Cancer Overview
https://www.cancer.org/cancer/types/colon-rectal-cancer.html - American Cancer Society Journals – Colorectal cancer screening: An update to the American Cancer Society guideline, 2026
https://acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.70083