ctDNA Assays in CRC: Impact on Clinical Practice


The potential impact that conclusions highlighted in a recent paper on postoperative MRD analysis in colorectal cancer may have on the management of patients with GI cancers.

Richard Kim, MD: In your opinion, Dr. Bustamante, what can we learn from this paper that may really impact our practice, just general physicians who treat colorectal cancer communities? Your thoughts in terms of how this paper may impact their practice or our practice?

Liliana Bustamante, MD: Specifically in the population that is being studied in this paper and I've had several patients over the past few years like this. These are patients that have done chemotherapy, usually in my setting and then go to surgery and are NED after surgery. I think doing this test, I would say with two negative tests at different standpoints, I think would give me some reassurance that I can just observe them for a while. And I can give reassurance to the patient that we're going to be hopefully in good grounds because of this paper, showing 100% overall survival in those patients that tested negative twice. It comes a little tricky- it becomes a little trickier for patients that have a positive circulating tumor DNA. I probably would do their surveillance a little closer and incorporate CEA, check-out maybe a little bit closer until I detect radiographic progression. If they had a lot of disease prior to surgery, I would have the discussion with the patient about whether it's worth doing some adjuvant therapy and seeing if the circulating tumor DNA becomes negative with the understanding that I have really no data to base this on. But I think, especially for the patients that test negative twice, there's a lot of anxiety that comes with having stage four disease and going through all the therapy and going through this big surgery. Those patients will get a lot of I guess, peace of mind and so would I, that they are likely do very well.

Richard Kim, MD: I think the, as you mentioned, I think the key point here is that if you do a two time points, that is a much of a stronger predictor of patient outcome. And I think that it's been clearly shown that here, along with other papers as well, that they studied in stage two and stage three colorectal cancer patient. I think the theme of more time points used, the better predictive of outcome has been consistent through most of the papers, at least in colorectal cancer.

Transcript edited for clarity.

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