Cologuard® Test is Worth Risk of a False Positive

Cologuard® is a brand of test that looks at DNA in stool for evidence of cancer. Certain DNA mutations are highly suggestive of cancer. In addition, Cologuard® does an immunochemical test looking for blood. Because it combines these two techniques, Cologuard® is more sensitive than only a test looking for blood. Compared with colonoscopy, Cologuard® is about 92% sensitive in finding cancers, meaning it will miss about 8 %. With improved sensitivity comes a lack of specificity, which means you could have a false positive result. The Cologuard® can say that you have an abnormality when a colonoscopy would indicate normal. False positives are more prevalent in older individuals.  <!–split–>

There are two reasons Cologuard® is still a reasonable choice, although it isn’t as good as a colonoscopy.

  1. A normal Cologuard® test prevents a need for colonoscopy, and a false positive would lead to the same colonoscopy you would have gotten anyway (although there is probably more anxiety after a false positive test).
  1. A person with an abnormal Cologuard® and a normal colonoscopy may be at risk for an abnormality that wasn’t found on colonoscopy. A study looking at people in this category found a 25% risk of abnormality on follow-up colonoscopy if the Cologuard® was abnormal again 1-2 years later.

Ask your doctor what he(she) recommends for you. Family history can also play a role in what your doctor may recommend.

Your Parish Nurse, Kara