Answers to 10 Frequently Asked Questions About Metastatic Breast Cancer

Receiving a diagnosis of metastatic breast cancer or knowing someone who has can be overwhelming, especially when there’s a lot to learn. So, during the CURE® Educated Patient Metastatic Breast Cancer Summit, two experts answered frequently asked questions about metastatic breast cancer.

From questions about scans, treatment advances to clinical trials, Dr. Jennifer M. Matro and Dr. Rebecca A. Shatsky, medical oncologists at the University of California San Diego Health, provided responses to patients at the summit.

Here are 10 answers to frequently asked questions about metastatic breast cancer.

1. How would the test Signatera (a type of circulating tumor DNA blood test) be used in monitoring metastatic breast cancer?

Matro and Shatsky: Currently, Signatera is not used in monitoring metastatic breast cancer. We use scans and labs/tumor markets to monitor. This is an area of research, though.

2. What about frequent nuclear bone scans?

Bone scans are done in combination with CT scans (imaging procedure to take detailed, two-dimensional pictures of the entire body) of the chest, abdomen and pelvis. It typically would be done approximately every three months or even more frequently if needed for suspected disease progression (worsening or spreading) or aggressive disease.

3. Since we are surviving metastatic breast cancer for longer periods, is there updated information about the frequency (especially for CT scans) regarding the risk of radiological scans? What should we do to reduce or monitor for issues?

There is no data whatsoever that suggests that frequent CT scans have any negative effects on patients with active metastatic breast cancer. CT scans are very necessary for disease monitoring and the benefits of monitoring metastatic breast cancer far outweigh any theoretical risks of radiation from CT scans.

4. Is it reasonable to request scans during monitoring and follow-up appointments? Surveillance of cancer for me is a physical exam and periodic blood tests. My monitoring feels inadequate because my original tumor was not palpable. I would feel confident about my health status if I was undergoing diagnostic testing as part of my appointments.

Scans are not used in stage 1 to 3 breast cancer for almost any patient. Insurance does not pay for them, as they have not been shown to improve outcomes.

5. If the first-line treatment is Kisqali (ribociclib)/Femara (letrozole), with the new data, what CDK inhibitor could patients switch to? Would hormone therapy chance as well?

Data from the phase 3 postMONARCH trial, presented at ASCO this year, suggested that changing the hormone therapy and changing the CDK inhibitor to Verzenio (abemaciclib) provides greater benefit than a new hormone therapy on its own. So, in the absence of other mutations, this may be an option for some patients.

6. Does Enhertu (trastuzumab deruxtecan) work for leptomeningeal disease?

Yes, there are emerging data that Enhertu is very beneficial in leptomeningeal disease and brain metastases.

7. Many patients with metastatic breast cancer die of brain metastases or leptomeningeal disease. Should a baseline brain MRI (a scan that takes pictures of the body’s anatomy and physiological processes) be done when a person’s disease becomes metastatic?

The development of leptomeningeal disease and the risk of brain metastases or leptomeningeal disease depends on the specific subtype of breast cancer patients have. The highest risk or rates are for HER2-positive and triple-negative breast cancer. Brain metastases are rarer in estrogen-positive HER2-negative breast cancer, but the rates are increasing as patients live longer. The rates of leptomeningeal disease are higher also in patients with lobular breast cancer. There is no data that suggests that routine brain MRIs in asymptomatic patients improve outcomes.

READ MORE: Oncologist Debunks Clinical Trial Myths

8. How often does hormone receptor (HR)-positive cancer mutate into a triple-positive cancer when it becomes metastatic?

This happens approximately 10% to 15% of the time, where the cancer recurs (comes back) in a different form than the initial presentation. That's why we always do a biopsy and receptor testing on newly diagnosed metastatic breast cancer.

LEARN MORE: Biomarker Testing Is Essential in HR-Positive Metastatic Breast Cancer

9. If a person does not live near a National Cancer Institute-designated cancer center, must they travel to the trial center? Does it make a difference if a person is in the state of the ongoing trial, such as California?

A patient must travel to wherever the trial they want to enroll in is being run. If they are in the state where the trial is being run and they want to hear more about it, they may be able to ask for a telemedicine visit to hear more about it. But to enroll, they will need to go there physically. If they want to get an opinion from a clinical trialist and don't live nearby, it's a great idea to ask for a telemedicine visit with a specific doctor at a big center that runs clinical trials.

10. If patients are reluctant to receive the standard of care and aren’t eligible for a trial, do doctors ever offer label treatments or try to get a trial drug on compassionate use (receiving promising but not-yet-approved drugs when no other treatment options are available)?

Unfortunately, doctors are not able to prescribe therapies that are not FDA-approved through compassionate use, unless the respective drug company allows doctors to, which is incredibly rare.

I only prescribe "off-label therapy" when there is a good clinical rationale for using that therapy and a good chance it might work based on pre-clinical data (this is for drugs that are already FDA-approved in other cancer types. We cannot do this with drugs that are not yet approved).

It would be against the oncology code of ethics to prescribe a therapy that does not have good data for its use and that may benefit the patient.

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