Practical Advice on the Use of ctDNA Testing in Breast Cancer


Closing out their discussion on circulating tumor DNA in breast cancer management, experts share closing advice on practical strategies to use testing in clinic.


Aditya Bardia, MD, MPH: In terms of what's exciting related to ctDNA (circulating tumor DNA), there are the upcoming planned studies with interventions. The idea being that if you detect ctDNA and then intervene, you can improve outcomes. That's exciting. The other thing that's exciting in the ctDNA space are these newer technologies that bring in methylation or other strategies—not just focusing on tumor DNA, but other strategies to increase the detection rate. At the end of the day, in the MRD (minimal residual disease) space, it's about the sensitivity of the assay, so you can detect the first instance where something is going to be a problem that needs to be intervened upon. Thus, the sensitivity of the assay is a critical piece. We look forward to newer assays that are even more sensitive than the existing ones.

Barry Rosen, MD: I think when we look at the ctDNA data that we have right now we're clearly at the beginning of the process. I encourage my surgery and medical oncology colleagues to recognize that we want to enroll our patients in registry trials, because really, every patient is a test case. This gives us dynamic information as we treat the patient and follow them. We can actually gain a great deal of insight just with an N-of-1 trial following that patient. And what's going to happen is the more studies that we do, the more collective knowledge that we get, the more meaningful this information will become. Hence, I really do believe that this is a dynamic test that is going to move us to even more precision management of our patients. And when you recognize that we have so very little to offer our breast cancer patients when it comes to systemic surveillance, I think that makes that even a higher priority.

Aditya Bardia, MD, MPH: Regarding the role of ctDNA and the management of breast cancer, I think ctDNA assays should be viewed as a liquid biopsy. It gives you information, not just about the presence of disease, but also the molecular type, which can be helpful for therapy selection in the metastatic setting. Thus, if you're thinking of tumor genotyping, plasma-based genotyping can be very valuable. And that essentially is what ctDNA assays are.

Transcript edited for clarity.

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