The Role of Circulating Tumor DNA in Breast Cancer Monitoring

Circulating tumor DNA, also referred to as ctDNA, are small pieces of DNA that are released into a person’s blood by tumor cells as they die, according to the National Cancer Institute. A blood sample can then be used to monitor risks of cancer recurrences, as well as to help plan treatment, or to find out how well treatment is working.

At the 42nd Annual Miami Breast Cancer Conference, Dr. Debu Tripathy sat down for an interview with CURE to discuss the utility of circulating tumor DNA in metastatic breast cancer where he emphasized that its role remains largely investigational. He discusses recent research on the use of circulating tumor DNA in breast cancer care and the critical need for further trials to guide treatment decisions.

Tripathy previously served as a professor and chairman of the Department of Breast Medical Oncology, Division of Cancer Medicine, at The University of Texas MD Anderson Cancer Center, in Houston, and as the editor-in-chief at CURE, prior to his retirement in March of 2025.

Transcript:

At the current time, circulating tumor DNA in patients with early-stage breast cancer, we know, is a risk factor for and predictor of recurrence. Right now, most of the work in this area is in the investigational setting, where trials are taking patients who've had early-stage breast cancer and are free of disease at the time, and drawing their blood serially every four to six months, depending on the study. If [the blood] becomes positive [for circulating tumor DNA], those patients are at high risk for recurrence.

The first thing studies will do is get a scan to see that [the patient] does not already have actual metastasis, and if they don't, then we'd consider them to have minimal residual disease. That means they have something there. We can't see it on scans yet, but they are at risk for progression, and the trials right now are looking at whether or not we can change their outcome by giving them a specific drug, either another hormonal therapy, or some of the targeted therapies.

In the case of triple-negative breast cancer, studies are looking at things like immunotherapy, and so far, the studies are very early, and we don't have a clear answer. We do know that in triple-negative cancer, the trials done so far don't seem to work, because these patients still go on to develop metastatic cancer. Right now, circulating tumor DNA, in my opinion, remains an investigational tool. Some people do it just as standard of care [and some of] these tests are approved. One of them is approved and covered, so you can get it done, and it is getting ordered by a lot of oncologists, but we don't know what to do with the results yet. We don't have a defined therapy for it, so we need more research in this area so that we can test the drugs that can give patients a second chance at being free of cancer. Those trials are in progress, and if people want to have it done, I think what they should do is look for a trial in which they can participate.

Transcript has been edited for clarity and conciseness

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