The Role of ctDNA in Gastrointestinal Cancer

Scott Kopetz, MD, PhD, FACP, MD Anderson Cancer Center, Houston, Texas, discusses the role of circulating tumor DNA (ctDNA) in gastrointestinal cancer at the 2019 Great Debates and Updates in Gastrointestinal Malignancies meeting.

Transcript:

Dr. Scott Kopetz:  At the Great Debates in GI Cancer meeting, we also discussed the role of circulating tumor DNA. This is an area that's rapidly moving. What is known at this point is that circulating tumor DNA is certainly in newly diagnosed, untreated metastatic patients is a very reliable and accurate, and rapid way to assess the genotyping of the patients.

It's commonly being incorporated into our clinical practice. There's also opportunities to improve outcomes for patients, utilizing the fact that circulating tumor DNA is a very rapid, a marker treatment response. The half-life is only two to three hours in circulation, so the level of circulating tumor DNA in the patient at a given time is a real-time measure of what the activity of the cancer is.

Finally, thinking about the role that circulating tumor DNA can play for discussion of the role of minimal residual disease management therapy, recognizing that this is a very specific marker, a high positive predictive value. When you see circulating tumor DNA that matches that seen in the patient's primary tumor, you can be assured that there's cancer somewhere.

It may take six to nine months for this cancer to appear, but it's there. As a result of that, there are opportunities to intervene. Some of the questions are, how do we use this information to improve treatment decision-making for patients or even novel therapy development? This is an area of substantial interest.

At the Great Debates in GI Cancer, we were very fortunate to have engagement with a number of patient advocates here. This is a key component of best management of patients, in my opinion. When I see patients in clinic, I'm commonly encouraging them to get involved in some of the patient advocacy groups, to seek out some of the resources available online from many of these different communities.

One of them, COLONTOWN, is a Facebook group that has matured and developed into a large community of advocates and patients and caregivers that are passionate about trying to improve outcomes for colorectal cancer patients. The discussions can run the gamut from disease survivorship, quality of life, as well as trying to identify novel therapies and clinical trials of benefit.

This is a tremendous resource for the patients, both to interact with and talk with the patients in a very similar situation to them, as well as seeking out the resources and opportunities for them, not only in their local area but also nationwide.