Richard M. Goldberg, MD: Stool DNA Test Technology Has Promise

Richard M. Goldberg, MD

Additionally, the DNA test can be repeated more easily than colonoscopy. However, this is one of the issues that require further evaluation. Currently, if a patient has a negative colonoscopy, we tell them that they don’t need another one for 10 years. With this DNA test, what happens if the test is performed more than once? If a patient has a negative test one year, do you perform the test annually? Will the sensitivity and specificity improve over time? We obviously don’t know the answer, but that is something that should be investigated further.

This study had several strengths. First, it was a large, multicenter trial conducted at both academic centers and practices. Second, every patient underwent a colonoscopy, which is the gold standard for detecting cancer. Third, the direct comparison of the DNA test with the standard FIT added power to the findings.

Nevertheless, the study did have a few limitations. For instance, we are unsure of how the DNA test performs in repeated testing and we don’t know what the acceptance rate would be among people who weren’t motivated to enroll in the trial. Even so, if the test is more appealing than colonoscopy, we may have the opportunity to reduce the incidence of colorectal cancer, which is a preventable disease, by detecting and removing premalignant polyps.

The FDA has heard evidence for this technology in the past few weeks and will eventually decide whether to approve for the indication of colon cancer screening. Even if the test is not approved, I think this technology remains interesting and could continue to be refined.

Another interesting aspect of this type of technology is that it could potentially detect cancers not just in the colon but in other areas of the digestive tract. We spit up and swallow phlegm from our lungs and throat constantly, so that DNA ends up in our gastrointestinal tract. So another question for the future is could this test be used to screen for more than just colon cancer?

Overall, this study demonstrates an exciting application of molecular genetics to screening. Hopefully, it is one of many future studies that will help us apply it in a way that will positively influence clinical outcomes for people.