Metastatic Breast Cancer: A Comprehensive Guide

Medically reviewed by Sara Tolaney, MD, MPH

Metastatic breast cancer (also referred to as advanced stage or stage IV breast cancer) is breast cancer that has spread (or metastasized) from the breast and adjacent lymph nodes to other parts of the body, such as the lungs, bones, brain, or liver.

Why does breast cancer spread?

Breast cancer spreads when the cancer cells penetrate the circulatory system and use either the blood stream or lymphatic system to travel to a new location, where they eventually land and form new tumors. While breast cancer can metastasize anywhere in the body, it usually spreads to either the lungs, bones, brain, or liver.

Regardless of where it spreads, the cancer will still be considered breast cancer if it originated in the breast. Breast cancer that has metastasized in the liver is not then considered liver cancer, for example. Your treatment options will typically depend on the biology of your breast cancer, among other factors, including the location of the metastasis.  

Some patients will develop metastatic breast cancer despite receiving therapy — including surgery, radiation, chemotherapy, or hormone therapy — for their original breast cancer diagnosis. This happens when their treatment does not destroy all of the breast cancer cells, and the surviving cancer cells eventually make their way into the circulatory system. 

Signs and symptoms of metastatic breast cancer

Signs and symptoms of metastatic breast cancer depend on where the cancer has spread to, and how much it has already grown. For patients with a history of breast cancer, new and persistent symptoms lasting more than two weeks should be evaluated.

“Patients know their body better than anybody else, and they should get anything that they notice is new and persistent evaluated,” says Sara Tolaney, MD, MPH, associate director of the Susan F. Smith Center for Women’s Cancers at Dana-Farber Cancer Institute. “If patients are concerned about anything, they should reach out to their oncologist.”

Below are signs and symptoms of that should be immediately discussed with a doctor. Note that some of these symptoms can be indicative of other health issues, and may not be related to cancer at all.

Lung metastasis

  • Difficulty breathing
  • Constant dry cough
  • Pain in the chest wall
  • Coughing up blood

Bone metastasis

  • Bone, back, neck, or joint pain
  • Multiple bone fractures
  • Swelling

Brain metastasis

  • Confusion
  • Vision disturbances
  • Difficulty with speech or movement
  • Weakness
  • Seizures
  • Severe headaches
  • Vomiting
  • Loss of balance

Liver metastasis

  • Swelling in the belly
  • Jaundice (a yellowing of the skin and whites of the eyes)
  • Severe abdominal pain
  • Itchy skin or a rash

Diagnosing metastatic breast cancer

Just as there is not one sign or symptom that indicates you have metastatic breast cancer, there isn’t a single test that can determine it. Any persistent health problems you are experiencing will likely lead to a scan, and the type of scan you receive depends on where the sign or symptom is located.

Typical scans include:

  • Computed tomography (CT or CAT) scan
  • Bone scans
  • Magnetic resonance imaging (MRI)
  • Positron emission tomography (PET or PET-CT) scan

If any abnormalities are found on the image, which is rare as often the symptoms you’re experiencing are not a result of metastatic breast cancer, your doctor will schedule a biopsy — a procedure in which a sample of tissue is removed for examination. If the sample comes back positive (it may take up to a week or so for the results), this may lead to additional testing. For example, your care team may look to test the tumor’s DNA for any mutations in the cancer’s genes. This information can be helpful to determine potential treatment options, including which clinical trials may be available.

Current treatment options

While metastatic breast cancer is not curable, it can be treatable. Today, with new therapies, women with metastatic breast cancer can have a high quality of life for many years.

Treatment plans for metastatic breast cancer are usually decided based on the cancer’s biological makeup and not the site of disease. The exception to the rule is brain metastasis. This is because many traditional treatment options cannot penetrate the blood brain barrier — a semipermeable barrier that protects the brain from potentially harmful substances. Treatments for brain metastasis will vary, but because of the location, radiation therapy is typically included.

Sara Tolaney, MD, MPH.

Recent advancements have resulted in more personalized, complex treatment plans. Today, an oncologist will look to target receptors, proteins, and even genetic mutations in cancer cells; all of which has helped to drastically improve the quality of care.  

Part of what makes metastatic breast cancer so difficult to treat is that the cancer cells will eventually stop responding to the current therapy. When this happens, you will have to move to a new line of treatment; changes can occur fairly often. Each subtype of breast cancer has multiple treatment options, and your oncologist will be able to go over all of them with you. 

If you are diagnosed with metastatic breast cancer, you will likely have routine imaging, typically every 2-3 months. These scans are designed to show if the treatment is working. Your care team will look to see if the tumors are stable or shrinking, and whether there are new tumor sites. Your oncologist will use the results to evaluate whether to continue your current therapy or switch to another treatment.

Clinical trials

Depending on your disease, you may be asked whether you’d like to participate in a clinical trial. Clinical trials are research studies in which people volunteer to test new treatments or interventions. They are the final step in a long process to determine whether a new treatment works and is safe.

Deciding if you’d like to participate in a clinical trial is a very personal decision, and one that is completely yours to make. The research collected from these trials are instrumental in making progress against cancer; and over the last decade, thanks to participating patients, they have led to the approval of new drugs for metastatic breast cancer.

Researchers have shown that agents targeting CDK 4/6, when combined with endocrine therapy, can effectively stop tumor growth, and improve survival. There is also recent data that hormone receptor positive breast cancers that harbor a mutation in the PI3-kinase pathway are sensitive to agents called PI3-kinase inhibitors and one such agent, alpelisib (Piqray), is approved in combination with hormonal therapy. 

Today there are numerous clinical trials focusing on metastatic breast cancer.  These studies allow access to novel agents before they have been FDA-approved, and can expand the number of treatment choices that are available to patients. People of all ages can take part in a clinical trial, and if this is something you’re interested in, make sure to ask you oncologist if there are any trials you may qualify for.

Learn more about clinical research and trials for metastatic breast cancer at Dana-Farber.

The latest research 

Metastatic breast cancer treatment is constantly evolving as a result of research that comes out of clinical trials and other avenues.

Today, researchers are focused on making treatment more precise in an effort to reduce toxicity and minimize side effects. There are also efforts underway to learn more about the genetic makeup of metastatic breast cancer cells. By understanding the cell’s DNA, scientists hope they can learn what is driving the cancer’s growth, and, in turn, find a way to shut those signals off. Researchers are also studying how immunotherapy might be used to improve treatment.

Here are some examples of recent advancements in care for each of the three breast cancer subtypes.

  • Hormone receptor-positive: In 2015, a clinical trial began to explore the combination of hormonal therapy with CDK4/6 inhibitors to better target hormone receptor-positive breast cancer. Results showed that a CDK4/6 inhibitor doubled a patient’s progression for survival, and can improve overall survival, and is now the standard therapy for some patients.
  • HER2-positive: Today, the standard treatment for HER2-positive metastatic breast cancer is a combination of taxane chemotherapy combined with two antibodies – trastuzumab (Herceptin) and/or pertuzumab (Perjeta). Both are directed at shutting off the HER2 receptors, and the combination has greatly improved patient survival.
  • Triple-negative: In 2019, the FDA approved the first immunotherapy drug (combined with chemotherapy) for patients with triple-negative breast cancer who test positive for the protein PD-L1.

Resources for metastatic breast cancer

If you have questions about your metastatic breast cancer or treatment options, it’s important to bring them to your oncologist. Breast cancer research is constantly evolving, and this can lead to confusion. Always be mindful of what you read, and when in doubt, bring the research to your cancer care team. 

There is also a growing number of resources for patients living with metastatic breast cancer. Many organizations offer informational forums, support groups, and even financial assistance.  

The Susan F. Smith Center for Women’s Cancers at Dana-Farber has a dedicated metastatic breast cancer support and education group, EMBRACE (Ending Metastatic Breast Cancer for Everyone), designed to provide resources and information for metastatic breast cancer patients. Part of their program includes an annual metastatic breast cancer forum, which covers the latest research, clinical trials, and overall tips for living with metastatic breast cancer.

If you’re looking for additional information or resources, try exploring one of the sites below: