A blood test for colon cancer is on the horizon. Here's what we know about 'Shield'

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Posted at 3:51 PM, Mar 14, 2024
and last updated 2024-03-14 17:41:43-04

(WXYZ) — The first blood test for colon cancer is on the horizon.  A study published Wednesday showed it detected the disease in more than 8 in 10 people. 

I do diagnose and care for patients with colon cancer. Unfortunately, it’s the second-highest cause of cancer deaths here in our country. A big part of the reason lies in people avoiding colon cancer screenings altogether. So I think an easy blood test would be a great option to offer some people. However, it would not replace a colonoscopy. And here’s why. During a colonoscopy, gastroenterologists like myself use a small flexible tube with a tiny camera to examine the entire colon. Not only can I see lesions or growths called polyps, I can also remove them as well. Removing them is important because little polyps can become cancerous over time. So, a colonoscopy is very accurate and preventative.

Now, how does this compare to the "Shield," the potential new blood test? In the study, over 7,800 participants underwent both the blood test and a colonoscopy. This blood test was designed to detect DNA fragments released by both cancerous tumor cells and precancerous growths. Overall, it was found to be 83% effective. Breaking it down, it had a sensitivity for stage I, II, or III colorectal cancer of 87.5%. But only a sensitivity of 13.2% for advanced precancerous lesions. So, the test was good at detecting colon cancer but not that great at detecting early-stage precancerous polyps. And that’s when treatment is most successful.

The "Shield" test did have its drawbacks. About 10% of the participants received false positive results as a follow-up colonoscopy confirmed that they did not have colon cancer. So, that could unnecessarily cause anxiety and worry in some people.

As for how often to have the blood test, the company recommends getting it done every three years. Whereas a colonoscopy is typically recommended every ten years for those with a clean bill of health.

Now, this blood test is not for everyone. It’s intended for those aged 45 and up who are at average risk and have no symptoms like blood in their stool. Having said that, it’s important to know that most colon polyps do not cause symptoms. And that’s why screening is strongly recommended. Colonoscopies are the gold standard for colon cancer screening. But I can see how the Shield blood test could be an alternative screening method – just like the stool test. Hopefully, if approved by the FDA later this year, it will help boost early detection rates and prevent the disease.

This Week on the Dr. Nandi Show

Suffering from high blood sugar due to diabetes can result in severe health complications over time. So, how can one lead a long and healthy life while minimizing the potentially life-altering effects of this chronic disease? That's precisely what Dr. Partha Nandi, MD, and his experts aim to tackle in this episode. You'll hear one guest share his journey from devastation upon diagnosis to resetting his outlook and becoming a fitness trainer and motivational speaker.  Also, experts discuss the difference between Type 1 and Type 2 along with potential treatments.  Plus, a board-certified naturopathic doctor shares alternative treatments for those with Type 2; a registered dietician presents healthy and delicious snacks, and a fitness instructor demonstrates three simple exercises anyone can do regardless of their fitness level. Tune in this Monday March 18th at 2:30 AM.