(WXYZ) — In today’s Health Alert, a panel of experts is evaluating whether a simple blood test designed to detect early signs of colon cancer is safe and effective. Developed by Guardant Health, the California-based biotechnology company is currently seeking FDA approval for its screening test called Shield.
It’s a blood test that’s geared for people aged 45 and up and who are also at average risk of colon cancer. So, those who’ve received a prior abnormal test result or have a personal or family history of colon cancer would not be eligible.
Now, the Shield test works by detecting DNA fragments released by both cancerous tumor cells and precancerous growths in blood samples.
The pros and cons of this test were revealed in a study with over 7,800 participants. The test had an 83% sensitivity rate in accurately identifying colon cancer and 90% specificity, which means how well it can identify people who don’t have the disease. Roughly 10% of the participants received a false positive. And 17% received a false negative. Now, the real downside is that the blood test has a low sensitivity of 13.2% for advanced precancerous lesions. Out of 1,116 participants with advanced precancerous lesions, the test was only positive for around 147 participants. So, the blood test was good at detecting colon cancer but comes with a risk of not detecting early-stage precancerous growths or polyps. This is unfortunate because missing them means losing the chance to stop or delay the start of cancer.
I often encounter resistance to colonoscopies in my office. So, the Shield test could be another tool that GI doctors like myself can offer patients. However, in my opinion, it would not replace other screening methods, especially colonoscopies. They are the gold standard for colon cancer screening. They only take about 20 minutes and can save lives. That’s because during a colonoscopy, a small flexible tube with a tiny camera allows the entire colon to be examined. I do many of these in my practice, and not only can I see lesions or growths, but I can also remove them.
Still, I can see how the Shield blood test could be an alternative screening method. If it helps more people get tested for this disease, I am all for it. Because colon cancer is the second most common cause of cancer deaths in the US. On average, we have around 50,000 deaths a year. And unfortunately, diagnoses among adults younger than 55 are on the rise. So, getting the recommended screenings is important so that more lives can be saved.
This Week on the Dr. Nandi Show
Dr. Partha Nandi brings awareness to glyphosate, a dangerous chemical found in weed killers that are likely sitting on your garage shelf. Thousands of people have brought suit against the maker of Roundup, saying their cancer is a direct result of the chemical. Hear from scientist Chris Portier, who has been an expert witness at several of the trials, and other researchers who say glyphosate is in our air, water, and soil. Plus, organic farmer Bob Quinn shares how his farm is thriving without chemical sprays. Tune in this Sunday, May 26th at 1 pm.
