Monitoring Metastatic Breast Cancer

Metastatic breast cancer (also called stage IV or advanced breast cancer) is not a specific type of breast cancer. It’s the most advanced stage of breast cancer.

Metastatic breast cancer is breast cancer that has spread beyond the breast and nearby lymph nodes to other parts of the body (most often the bones, lungs, liver or brain).

Metastatic breast cancer can respond to many different drug therapies. This means the drugs can shrink the tumors.

However, over time, tumors can become resistant (stop responding) to drugs used in metastatic breast cancer treatment.

How is metastatic breast cancer monitored?

If you have metastatic breast cancer, you’ll be monitored (checked) regularly to see if the cancer is responding to treatment. This is called “restaging.”

Tests may include a physical exam, blood tests and/or imaging tests (such as an X-ray, CT scan, PET scan, bone scan or MRI).

These tests help show whether or not your current treatment is working. If it’s no longer working, your oncologist will change your treatment or discuss other options.

Learn more about changing drug therapies.

Changing drug therapies

Some metastatic breast cancer cells need specific proteins or cell pathways to grow. Drugs that target the proteins or pathways can slow or stop the growth of these cancer cells for a period of time.

You can think of the proteins as traffic signs and the pathways as roads. Breast cancer cells must pass through the signs to continue along the road.

If the cancer cell hits a roadblock, such as a drug that targets the protein, it can’t continue down that pathway.

At some point however, the cancer cell finds a detour around the roadblock and uses another pathway to continue to grow.

Metastatic breast cancers often develop resistance to drugs, so it’s common to change therapies multiple times.

You usually start a drug therapy and then see whether:

  • It controls the growth of the cancer
  • The side effects can be managed

If the treatment is working at the time of restaging (and the side effects aren’t too bad), the treatment is usually continued.

If the treatment is no longer working or if you’re having a lot of side effects, your oncologist may switch you to a different drug. Your oncologist may also change the dose or schedule of the treatment to reduce side effects.

Blood tests for tumor markers

In some cases, blood tests for tumor markers may be used to help monitor metastatic breast cancer to see if the cancer is responding to treatment.

For example, you may have blood tests for cancer antigen 15-3 (CA15-3) or cancer antigen 27.29 (CA27.29) [4]. These tests are similar. Health care providers usually check one, but not both of these blood tests.

Whether the tumor marker test score rises or falls over time may give some information on tumor response to a drug or tumor spread.

Tumor marker tests are not helpful in every case though. Some people with rising tumor marker levels don’t have tumor growth, and some people with tumor growth have normal or unchanged tumor marker levels. Small changes in tumor marker levels are not usually of major clinical importance.

Health care providers don’t make treatment decisions based on tumor marker testing alone. They may combine findings from a tumor marker test with information on symptoms and findings from imaging tests (such as bone scans). This combined information can help your health care providers understand if a treatment is working well for your cancer.

Talk with your health care provider about whether it may be helpful to have tumor marker testing.

Scan anxiety (scanxiety)

It’s normal to feel anxious before scans or other tests to see if the cancer is responding to treatment. Some call this scan anxiety or scanxiety.

If it helps, talk to a friend or family member, or bring them with you to the appointment.

It’s also normal to feel anxious while you wait for your results. Try to do something to take your mind off the wait. For example, stay busy and do things you enjoy. Or talk with your family and friends if that helps you feel supported while you wait.

You can also talk with your health care provider about ways to cope with stress before scans or while you’re waiting for results.

Learn more about ways to cope with stress, such as mindfulness meditation.

Susan G. Komen® Breast Care Helpline

Calls to the Komen Breast Care Helpline are answered by a trained and caring staff member Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. The helpline provides free, professional support services to anyone with questions or concerns about metastatic breast cancer, including people diagnosed and their families.

Call the helpline at 1-877 GO KOMEN (1-877-465-6636) or email

Se habla español.

Clinical trials

Clinical trials offer the chance to try new treatments and possibly benefit from them.

Many clinical trials are available. Some are for the first treatment a person might get for their metastatic breast cancer, and others are for treatments later in the disease course. Consider joining a clinical trial when you’re newly diagnosed, when your oncologist is considering changing treatments or when there are limited treatment options.

Susan G. Komen® Breast Care Helpline

If you or a loved one needs information or resources about clinical trials, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877- 465- 6636) or email

Se habla español.

Metastatic Trial Search

The Metastatic Trial Search is a web-based clinical trial matching tool that can help you find clinical trials that fit your needs.

Learn more about clinical trials for people with metastatic breast cancer.

Learn what Komen is doing to help people find and participate in breast cancer clinical trials, including trials supported by Komen.


  • If you or a loved one needs more information about metastatic breast cancer, contact the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email All calls are answered by a trained specialist or oncology social worker, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. Se habla español.
  • Komen Patient Navigators can help guide you through the health care system as you go through a metastatic breast cancer diagnosis and treatment. They can help to remove barriers to high-quality breast care. For example, they can help you with insurance, local resources, communication with health care providers and more. Call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email to learn more about our Patient Navigator program, including eligibility.
  • We offer an online support community through our closed Komen Metastatic Breast Cancer (Stage IV) Group. The Facebook group provides a place where those living with metastatic breast cancer, and those who love them, can find support, friendship and information. Click the link above or visit Facebook and search for Komen Metastatic Breast Cancer (Stage IV) Group and request to join.
  • Our free MBC Impact Series provides people living with metastatic breast cancer and their loved ones a safe, collaborative space to gather information related to metastatic breast cancer and discover practical resources to help make decisions for improved physical and emotional health. To learn more and register visit
  • Our Real Pink podcast series covers many relevant topics for people living with metastatic breast cancer and caregivers.
  • Our fact sheets, booklets and other education materials offer additional information.

Updated 06/23/23


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