Blood Testing for Colorectal Cancer Screening Joins Recommendations for the First Time

In a significant shift for cancer prevention, blood testing for colorectal cancer screening has been added to official recommendations for the very first time. The American Cancer Society announced the change as part of an updated guideline, expanding the menu of options available to adults seeking to catch colon and rectal cancers early.

The move aims to address a persistent and troubling problem: too many people are skipping screening altogether, even as cases of colorectal cancer rise among younger adults.

The Gold Standard Remains the Colonoscopy

Despite the new addition, the colonoscopy still holds its place as the gold standard for detecting colorectal cancer, which begins in either the colon or the rectum. Performed under anesthesia, the procedure allows doctors to closely examine these areas for early warning signs of disease.

For those who prefer to avoid an invasive exam, other options have long been available. These include alternative visual exams and stool-based tests, which remain widely recommended. While the idea of collecting a fecal sample makes some people uncomfortable, these tests have proven to be valuable tools in early detection.

Why a New Option Was Needed

The central challenge is straightforward: many people simply don’t complete the available screening options, whether due to reluctance, discomfort, or access barriers. This gap in screening has become especially concerning given the rise in colorectal cancer cases at younger ages.

To help reach people who might otherwise go unscreened, the American Cancer Society has now embraced blood testing as an additional choice. The updated guideline, released Wednesday, recommends blood-based screening for adults aged 45 and older who are at average risk and who have either declined or not completed visual exams and stool tests.

The Shield Test and Other New Additions

The specific blood test the group recommends is the Shield test, developed by the biotech company Guardant Health and approved by the U.S. Food and Drug Administration in 2024.

The guideline didn’t stop at blood testing. It also incorporated additional stool-based options:

• Cologuard Plus, an upgraded version of the existing Cologuard test.
• ColoSense, a new FDA-approved test developed by the biotech company Geneoscopy.

Both are at-home stool tests, in which samples are collected at home and mailed to a lab. There, the tests detect molecular markers associated with colorectal cancer, offering a convenient and non-invasive way to screen.

Why Blood Testing Isn’t the First Choice

Importantly, the blood test is not meant to replace the more established options. The researchers behind the updated guidelines, published in a report in CA: A Cancer Journal for Clinicians, made clear that blood-based tests should be recommended only to individuals who decline or do not complete the preferred screening methods, namely colonoscopies or stool-based tests.

The reason comes down to sensitivity. According to Dr. William Dahut, chief scientific officer for the American Cancer Society, a blood-based test is not the first choice because it is less effective at detecting precancerous polyps than other options. Even so, he emphasized that it represents the right option for the right population of patients.

Dahut highlighted the practical value of expanding choices, noting that many people simply can’t or won’t undergo a colonoscopy or collect their own stool for testing. By offering more options, he hopes more people will get screened, allowing cancers to be caught earlier and more patients to be cured.

Why Early Screening Matters So Much

The stakes of screening are high, and the benefits of early detection are dramatic. When colorectal cancer is diagnosed before symptoms appear, treatment can begin sooner, significantly improving survival odds.

The statistics tell a compelling story. It’s estimated that more than 90% of people who detect colorectal cancer at stages I and II will survive at least the next five years. By contrast, when cancer is found at a more advanced stage, it may have already spread to surrounding regions or other parts of the body, making it far harder to treat and reducing the patient’s chances of survival regardless of age.

Screening as Prevention, Not Just Detection

Beyond catching cancer early, screening can actually help prevent colorectal cancer from developing in the first place. This is because nearly all colorectal cancers begin as precancerous polyps in the colon or rectum.

During a visual exam like a colonoscopy, these polyps can be identified and removed before they ever turn cancerous. Stool tests can also detect signs of precancerous polyps, and a positive result is followed up with a colonoscopy, which then offers an opportunity for prevention. This preventive dimension is one reason colonoscopies remain so highly valued.

Expert Reactions to the New Guidelines

The updated recommendations have drawn praise from medical experts who see them as a pragmatic step forward. Dr. Ursina Teitelbaum, a professor of gastrointestinal oncology at the University of Pennsylvania who was not involved in the recommendations, described the guideline as forward-thinking and reality-based.

She acknowledged that blood-based testing remains imperfect, since it may miss early-stage cancers and precancerous lesions. Yet she invoked the principle that “perfect” should not be the enemy of good, noting that the new guidelines recognize the need to broaden screening, particularly among younger, vulnerable populations.

More Tests Could Be Coming

The Shield test may be the first blood-based test to earn a recommendation, but experts believe it won’t be the last. Dr. Scott Kopetz, a gastrointestinal medical oncologist at The University of Texas MD Anderson Cancer Center, expressed optimism about the future of the technology.

He noted that this first blood-based test will likely be followed by others, with the hope that future versions will reduce barriers to screening even further while improving performance. In his view, the technology will only continue to improve from here.

At the same time, Kopetz offered an important caution. Because blood-based screening does not currently perform as well at detecting precancer as other options, it should be reserved for individuals who will not complete other recommended screenings. He stressed that patients who would otherwise be willing to undergo a colonoscopy or stool-based test should not switch to the blood-based assays.

The Bigger Picture

The addition of blood testing to colorectal cancer screening recommendations reflects a thoughtful balance between scientific rigor and real-world practicality. While it isn’t a replacement for the most sensitive methods, it offers a valuable lifeline for people who would otherwise avoid screening entirely.

By meeting patients where they are and lowering the barriers to participation, the new guideline has the potential to bring more people into the screening fold. And in the fight against colorectal cancer, where early detection can mean the difference between a highly survivable diagnosis and a far more dangerous one, expanding access in this way could ultimately save lives.

Final Thoughts

As colorectal cancer continues to affect more people, including younger adults, the importance of accessible screening has never been clearer. The introduction of blood testing for colorectal cancer screening marks a meaningful step toward ensuring that no one falls through the cracks simply because the traditional options didn’t work for them.

For now, experts agree on the core message: the best screening test is the one you’ll actually complete. Whether through a colonoscopy, a stool test, or the newly recommended blood test, getting screened remains one of the most powerful steps anyone can take to protect their health.

This is a health-related topic, and individual circumstances vary. Anyone with questions about colorectal cancer screening should consult a healthcare provider to determine the most appropriate option for their personal situation.