Did you know your blood and tissue samples can be used to help monitor your breast cancer and detect recurrence through MRD testing? When you have a biopsy or breast cancer surgery, the removed tissue is kept as it may be used in testing that helps determine your treatment plan or monitoring strategy.
One of the tests your samples may undergo is MRD testing, a highly sensitive tool that can analyze blood samples for evidence that there are tumor cells still lingering after a treatment such as surgery or chemotherapy. MRD testing isn’t new. It has been used for years in other cancers, and while it is not yet a standard of care for breast cancer, it is for blood cancers like leukemia. MRD is now beginning to emerge as a powerful disease monitoring option for some breast cancer patients.
What Is MRD?
MRD is a term used to describe a very small number of cancer cells that remain in the body during or after treatment. MRD testing detects tiny amounts of circulating tumor DNA (ctDNA), which are fragments of genetic material shed by cancer cells into the tissue or bloodstream. Think of ctDNA like breadcrumbs left behind by cancer cells in your body. Standard imaging scans, like mammograms or ultrasound, can only detect tumors once they’ve grown large enough to be visible, but MRD testing can identify cancer DNA at much lower levels, even before a tumor is seen using imaging technology. MRD testing may play a role in helping to plan your treatment, find out how well your treatment is working or see if the cancer has come back.
Understanding Different Types of MRD Tests
Knowing the differences between MRD tests can help you and your doctor determine which one may be right for you. MRD testing falls into two categories based on whether or not a tumor tissue sample is used.
Tumor-informed tests analyze a sample of your tumor collected during a biopsy or surgery to identify mutations, or changes in the DNA, that drive cancer growth. Each person’s cancer carries a combination of mutations that differs from anyone else’s. This unique genetic profile of your cancer can be referenced when analyzing blood samples to detect ctDNA molecules that contain any of these mutations, enabling you and your doctor to track how well a treatment is working and to detect any signs that the cancer is returning. This personalized approach makes the test highly specific — reducing false positives (when people are incorrectly shown to have a disease) and improving accuracy in detecting residual cancer and recurrence.
Tumor-naive tests, on the other hand, do not require a baseline tumor sample. Instead, they analyze blood for a panel of commonly observed cancer-related mutations. This makes them more accessible, especially for patients without stored tumor tissue. However, because they are not tailored to an individual’s unique tumor profile, they may be less sensitive at detecting minimal residual disease, especially at very low levels, because they are screening for a wide range of mutations that may not be relevant to a specific patient. As a result, this can increase the risk of false negatives. Tumor-naive tests remain an important tool, especially for patients without a stored tumor sample.
It’s important to note MRD testing is not a replacement for imaging — tools like MRIs, CT scans or mammograms remain critical in monitoring for signs of disease or recurrence. However, MRD may be a complement to routine scans by helping look for biological signs of cancer returning earlier, prompting closer monitoring or additional imaging. Meanwhile, imaging confirms and localizes any potential regrowth of tumors, so doctors can see where cancer may be present to assess the need for treatment. Using both tools together allows for earlier intervention and more personalized care decisions.
How MRD Testing Can Impact Your Care
- If MRD is negative: This indicates no cancer DNA was found in your blood, suggesting that the current risk of recurrence is low.
- If MRD is positive: This may indicate residual cancer cells were found in your blood, helping your doctor decide whether additional treatment or closer monitoring is needed.
While MRD testing is not part of the standard of care for breast cancer at this time, it’s a good idea to discuss with your doctor whether MRD testing may be right for you and if it fits into your overall care plan as a recent study demonstrated that this method of testing ctDNA may not be reliable for patients that have undergone neoadjuvant therapy. In some cases, it may result in falsely reporting that the cancer is gone when in fact it is not.
The Future of MRD in Breast Cancer Care
MRD testing can provide additional information to doctors as they work to track and manage someone’s breast cancer and risk of recurrence. Tests including MRD can help to further personalize the future of breast cancer care. By detecting cancer DNA at extremely low levels, MRD testing is one option that might allow for earlier intervention and more tailored treatment strategies.
As research advances, MRD is expanding its role in breast cancer care, providing patients and doctors with real-time insights into disease progression. Innovations like this are paving the way for more proactive and individualized approaches to treatment, bringing us closer to improved outcomes and greater peace of mind for patients.
MRD is not currently in breast cancer care guidelines. Researchers are still studying how MRD may play a role in breast cancer care. Talk to your doctor about what tests may be appropriate for you.
Resources to Learn More:
Talking to Your Doctor with Dr. Reshma Jagsi
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