A New Blood Test for Colorectal Cancer - What You Need to Know - September 2024

Colorectal cancer (CRC) is a major health concern in the United States, being the second deadliest cancer, responsible for around 53,000 deaths in 2022 alone. But here’s the thing—many of these deaths could have been avoided if more people had gotten screened. The sooner colorectal cancer is detected, the better the chances of beating it. That’s why regular screening is so important. But not everyone is eager to undergo a colonoscopy, the most common screening method. So, when a new blood test for colorectal cancer detection was introduced, it seemed like a potential game-changer. But how does it really stack up against the tests we already have? Let’s break it down.

How the New Blood Test Works

The new blood test for colorectal cancer relies on something called cell-free DNA (cfDNA). When cells die, they release tiny fragments of DNA into the bloodstream. This includes cancer cells, which have their own unique DNA patterns. The test looks for these patterns in your blood, focusing on two key areas: the amount of tumor DNA and specific genetic changes linked to colorectal cancer. Unlike some older blood-based tests that only measure one or two biomarkers, this cfDNA test uses a more comprehensive approach by combining several indicators of cancerous activity, such as mutations in genes like KRAS and APC, abnormal methylation patterns, and DNA fragmentation profiles. The idea behind this test is that it could offer a simpler, less invasive way to screen for CRC, potentially increasing the number of people who get screened.

What the Research Shows

A recent study, published in the New England Journal of Medicine in 2024, tested this new blood test on nearly 8,000 people aged 45 to 84 who were already scheduled for a colonoscopy. Among them, 65 were found to have colorectal cancer. The blood test successfully detected cancer in about 83% of those cases. While this sounds pretty good, the test’s ability to detect early-stage cancer wasn’t as strong—especially when it came to cancers that were just starting to develop. In fact, the test missed almost half of the Stage I cancers, the kind that are most treatable if caught early.

For those of us who aren’t experts, that means the test is better at finding more advanced cancers than it is at catching the disease early when it’s easier to treat. And when it comes to detecting pre-cancerous growths—things like polyps that could turn into cancer down the line—the test caught only 13% of them.

My Opinion on the New Blood Test

As a primary care physician deeply invested in the early detection and prevention of colorectal cancer, I have concerns about this new blood test. While it may offer some value for patients who are hesitant to undergo more invasive procedures, it doesn’t yet match the effectiveness of more established screening methods. In my professional opinion, which is shared by many experts in the field of colorectal cancer, this blood test is not ready to replace a colonoscopy.

A colonoscopy remains the most effective tool we have—not only for detecting cancer but also for preventing it by removing polyps before they become dangerous. While the new blood test might be a useful starting point for some patients, it’s important to understand that a positive result from this test would still need to be confirmed by a colonoscopy. Given its limitations, particularly in detecting early-stage cancers and precancerous lesions, I believe that colonoscopies and stool-based tests should remain the cornerstone of colorectal cancer screening.

How Does This Test Compare to Others?

So, how does this new blood test compare to other colorectal cancer screening options? Here’s a quick rundown of the main tests, ranked from best to worst for early detection, along with the recommended testing frequency for each:

1. Colonoscopy

• Detection Power: Best

• Frequency: Every 10 years if normal

• Why It’s Great: A colonoscopy allows doctors to see the inside of your colon and remove polyps on the spot, preventing them from turning into cancer. It’s the gold standard for a reason.

2. Stool DNA Test (e.g., Cologuard)

• Detection Power: Very Good

• Frequency: Every 3 years

• Why It’s Great: This at-home test checks your stool for DNA changes and blood that could signal cancer or pre-cancerous growths. It’s much better at finding early-stage cancers compared to the new blood test.

3. GRAIL Gallery Test

• Detection Power: Good (for multiple cancers, including CRC)

• Frequency: Not specified (typically part of a multi-cancer screening strategy)

• Why It’s Notable: This blood test is designed to detect multiple types of cancer early, including colorectal cancer, but its overall sensitivity for CRC alone is around 14%. It’s more useful as part of a broader cancer screening strategy rather than a CRC-specific test.

4. CT Colonography (Virtual Colonoscopy)

• Detection Power: Good

• Frequency: Every 5 years

• Why It’s Good: This imaging test provides a detailed picture of your colon. It’s less invasive than a traditional colonoscopy, but you still need to prep for it like you would for a colonoscopy.

5. EPISEEK Test

• Detection Power: Fair

• Frequency: TBD (emerging test, likely more frequent)

• Why It’s Emerging: The EPISEEK test analyzes epigenetic changes in DNA to detect colorectal cancer. While it’s a promising blood-based option, it is still in the early stages of validation and may not yet be as reliable as more established tests.

6. Fecal Immunochemical Test (FIT)

• Detection Power: Fair

• Frequency: Every year

• Why It’s Decent: This simple test checks for hidden blood in your stool, which can be a sign of cancer. It’s less powerful than the options above but still valuable for catching cancer early.

7. New Blood Test (cfDNA Test)

• Detection Power: Poor (for early-stage cancer)

• Frequency: TBD (likely more frequent due to lower detection power)

• Why It’s Lacking: While it’s convenient and can be done with a simple blood draw, its ability to catch early-stage cancer is not strong enough to replace the other tests.

The Bottom Line

When it comes to colorectal cancer screening, colonoscopies still reign supreme because of their ability to not only detect but also prevent cancer by removing polyps. For those who want less invasive options, stool DNA tests like Cologuard offer a strong alternative, especially for early detection. The GRAIL Gallery Test and EPISEEK Test represent newer, cutting-edge technologies, but they are currently more complementary than primary tools for CRC screening.

Ultimately, the best test is the one that gets done regularly. So, talk to your doctor about the screening method that best fits your health needs and lifestyle.

About Elite Medical Associates

At Elite Medical Associates, we are dedicated to advancing the practice of medicine by integrating cutting-edge science with personalized care. Our concierge and longevity medicine practice is designed to offer you the highest level of personalized attention, focusing on preventive care, early detection, and strategies to extend your healthspan. We believe that staying ahead of the curve in medical advancements, like the latest colorectal cancer screenings, is key to providing our patients with the best possible care. If you’re interested in a more personalized approach to your health, including comprehensive screenings and preventive strategies, Elite Medical Associates is here to guide you every step of the way.

Disclaimer

This article is for general informational purposes only and does not constitute the practice of medicine or other professional healthcare services. The information provided herein should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare providers with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read in this article.