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 to treat metastatic breast cancer.

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 health care provider will change your treatment.

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.

Because metastatic breast cancers often develop resistance to drugs, 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 help 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. 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.

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 tumor marker testing is right for you.

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, if possible. You can also talk with your health care provider about ways to cope with this stress.

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

Susan G. Komen®’s Breast Care Helpline:
1-877 GO KOMEN (1-877-465-6636)

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 breast cancer, including people diagnosed with breast cancer and their families.

You can also email the helpline at

Se habla español.

Clinical trials

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

Consider joining a clinical trial when your oncologist is considering changing treatments, before starting a new treatment 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.


Komen Perspectives

Read our perspective on metastatic breast cancer.*

Learn More


  • If you or a loved one needs more information about breast health or 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 breast cancer diagnosis. 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 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. Visit Facebook, search for Komen Metastatic Breast Cancer (Stage IV) Group and request to join the closed group.
  • 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 MBC and discover practical resources to help make decisions for improved physical and emotional health. To learn more and register visit
  • Our podcast series Real Pink covers many relevant topics for people living with metastatic breast cancer and caregivers.
  • Our fact sheets, booklets and other education materials offer additional information.

*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date.

Updated 06/30/22


Questions to Ask Your Doctor

Research Fast Facts