New cancer screening test now available

You may have heard about Cologuard, a stool-based colorectal screening test that received FDA approval in 2014 and now is available by prescription. The noninvasive test detects DNA from abnormal cells and hemoglobin from red blood cells that may indicate the presence of certain kinds of growths that could be cancerous, such as colon cancer, or precursors to cancer.

While colonoscopies remain the gold standard in colon cancer prevention, Cologuard is another weapon in the screening arsenal. If you’re wondering if this colorectal test is correct for you, I encourage you to speak with your physician. In the meantime, I’ll address some frequently asked questions:

What is Cologuard? Cologuard is a stool DNA test used for colorectal cancer screening. It received Food and Drug Administration approval in August 2014 and now is available throughout the United States. The test is only available by prescription from your doctor.

Is Cologuard recommended for everyone? The test can be used by men and women age 50 and older who are at average risk for colon cancer. It should not be used by those who are at higher risk for colon cancer, including individuals with a history of inflammatory bowel disease or a known family history of colon cancer or precancerous polyps.

How does Cologuard work? If cancerous or precancerous tissue is present in your colon, those abnormal cells may be picked up by stool as it passes through the digestive tract. Cologuard uses laboratory technology to find DNA from these abnormal cells. Cologuard is not a genetic test; it only looks for altered DNA associated with colon cancer and precancerous cells in the colon.

How is the Cologuard test performed? A stool sample is collected at home with a kit that is provided by Cologuard. This process involves placing a plastic collection bucket on the toilet seat, collecting the stool sample, scraping the sample with a collection probe and placing the remaining stool sample in a liquid solution. The sample needs to be shipped to a laboratory for evaluation within three days of collection. A physician will review the results of the study and order additional tests as needed.

How do I prep for the Cologuard test? The test requires no prep or dietary changes.

How is Cologuard different from other stool-based tests? Other stool tests, including the fecal immunochemical test (FIT), work by detecting tiny amounts of blood in the stool. Unlike Cologuard, those tests do not look at DNA. In clinical studies that included more than 10,000 participants, Cologuard was more sensitive than the FIT test in detecting colorectal cancer; however, Cologuard also had more false positives. Cologuard was positive in 13 percent of people without cancer compared to the FIT test’s 5 percent false-positive rate. The FIT test, which costs $25, is much less expensive than Cologuard, which is $500-$599.

How accurate is the Cologuard test? In clinical studies, Cologuard found 92 percent of colon cancers and 42 percent of advanced precancerous tissue in the colon, including colon polyps. It missed 8 percent of colon cancers and nearly 60 percent of the advanced precancerous tissue. As noted above, it also had a 13 percent false positive rate.