Metastatic Breast Cancer

Metastatic Breast cancer

Cancer begins when healthy cells change and grow out of control, forming a mass or sheet of cells called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.

When breast cancer is limited to the breast and/or nearby lymph node regions, it is called early-stage or locally advanced. Read about these stages in a different guide on   Denvax.When breast cancer spreads to an area farther from where it started to another part of the body, doctors say that the cancer has “metastasized.” They call the area of spread a “metastasis,” or use the plural “metastases” if the cancer has spread to more than 1 area. The disease is called metastatic breast cancer. Another name for metastatic breast cancer is “stage IV (4) breast cancer” if it has already spread beyond the breast and nearby lymph nodes at the time of diagnosis of the original cancer.

Doctors may also call metastatic breast cancer “advanced breast cancer.” However, this term should not be confused with “locally advanced breast cancer,” which is breast cancer that has spread to nearby tissues or lymph nodes but not to other parts of the body.

Metastatic breast cancer may spread to any part of the body. It most often spreads to the bones, liver, lungs, and brain. Even after cancer spreads, it is still named for the area where it began. This is called the “primary site” or “primary tumor.” For example, if breast cancer spreads to the lungs, doctors call it metastatic breast cancer, not lung cancer. This is because the cancer started in breast cells.

Metastatic breast cancer can develop when breast cancer cells break away from the primary tumor and enter the bloodstream or lymphatic system. These systems carry fluids around the body. The cancer cells are able to travel in fluids far from the original tumor. The cells can then settle and grow in a different part of the body and form new tumors.

Most commonly, doctors diagnose metastatic breast cancer after a person previously received treatment for an earlier stage (non-metastatic) breast cancer. Doctors sometimes call this a “distant recurrence” or “metastatic recurrence.” This can happen at any time after someone is diagnosed with breast cancer, even a few decades later.

Sometimes, a person’s first diagnosis of breast cancer is when it has already spread to other parts of the body. Doctors call this “de novo” metastatic breast cancer or stage IV breast cancer.

Types of breast cancer

There are several types of breast cancer, and any of them can metastasize. Most breast cancers start in the ducts or lobules and are called ductal carcinomas or lobular carcinomas.

• Invasive ductal carcinoma. These cancers start in the cells lining the milk ducts and make up the majority of breast cancers.
• Invasive lobular carcinoma. This is cancer that starts in the lobules, which are the small, tube-like structures that contain milk glands.

Some breast cancers are made up of a combination of types of breast cancers. These are sometimes called invasive mammary cancers.

Breast cancer can develop in women and men. However, male breast cancer is rare, accounting for less than 1% of all breast cancers.

Breast cancer subtypes

Breast cancer is not a single disease, even among the same type of breast cancer. When you are diagnosed with breast cancer, your doctor will recommend lab tests on the cancerous tissue. If you have been diagnosed with metastatic breast cancer after being treated for non-metastatic breast cancer, your doctor may want to repeat the tests to see if the tumor’s cells have changed in any way. These tests will help your doctor learn more about the cancer and choose the most effective treatment plan. Metastatic breast cancer is usually not curable, but it can be treatable. Many people continue to live well for many months or years with the disease, and treatments continue to improve.

Tests can find out if your cancer is:

• Hormone receptor-positive. Breast cancers expressing estrogen receptors (ER) and/or progesterone receptors (PR) are called “hormone receptor-positive.” These receptors are proteins found in cells. Tumors that have estrogen receptors are called “ER-positive.” Tumors that have progesterone receptors are called “PR-positive.” These cancers may depend on the hormones estrogen and/or progesterone to grow. Hormone receptor-positive cancers can occur at any age. However, they may be more frequent in people who have gone through menopause. Menopause is when the body’s ovaries stop releasing eggs. About 60% to 75% of breast cancers have estrogen and/or progesterone receptors. If the cancer does not have ER or PR, it is called “hormone receptor-negative.”
• HER2-positive. About 15% to 20% of breast cancers depend on the gene called human epidermal growth factor receptor 2 (HER2) to grow. These cancers are called “HER2-positive” and have many copies of the HER2 gene or high levels of the HER2 protein. These proteins are also called “receptors.” The HER2 gene makes the HER2 protein, which is found on the cancer cells and is important for tumor cell growth. HER2-positive breast cancers grow more quickly. They can also be either hormone receptor-positive or hormone receptor-negative (see above). Cancers that have no HER2 protein are called “HER2-negative.” Cancers that have low levels of the HER2 protein are called “HER2-low.”
• Triple-negative. If the breast tumor does not express ER, PR, or HER2, the tumor is called “triple-negative.” Triple-negative breast cancers make up about 15% of invasive breast cancers. This type of breast cancer seems to be more common among younger women, particularly younger Black women. Triple-negative breast cancer may grow more quickly. Triple-negative breast cancers are the most common type of breast cancer diagnosed in people with a BRCA1 gene mutation. This means that you may be more likely to have a BRCA1 gene mutation if you have been diagnosed with triple-negative breast cancer. All people younger than 60 with triple-negative breast cancer should be tested for BRCA gene mutations. Find more information on BRCA gene mutations and breast cancer risk.

How many people are diagnosed with metastatic breast cancer?

In 2023, an estimated 300,590 people (297,790 women and 2,800 men) in the United States will be diagnosed with invasive breast cancer. Breast cancer is the most common cancer in women in the United States, excluding skin cancer. Worldwide, female breast cancer has now surpassed lung cancer as the most commonly diagnosed cancer. An estimated 2,261,419 women worldwide were diagnosed with breast cancer in 2020.

In the United States, 6% of women have metastatic breast cancer when they are first diagnosed.

Breast cancer is the second most common cause of death from cancer in women in the United States. It is estimated that 43,700 deaths from this disease (43,170 women and 530 men) will occur in the United States in 2023. Worldwide, female breast cancer is the fifth leading cause of death. In 2020, an estimated 684,996 women across the world died from breast cancer. Metastatic breast cancer causes the vast majority of deaths from the disease.

What is the survival rate for metastatic breast cancer?

There are different types of statistics that can help doctors evaluate a person’s chance of recovery from metastatic breast cancer. These are called survival statistics. A specific type of survival statistic is called the relative survival rate. It is often used to predict how having cancer may affect life expectancy. relative survival rate looks at how likely people with metastatic breast cancer are to survive for a certain amount of time after their initial diagnosis or start of treatment compared to the expected survival of similar people without this cancer.

Example: Here is an example to help explain what a relative survival rate means. Please note that this is only an example and not specific to this type of cancer. Let’s assume that the 5-year relative survival rate for a specific type of cancer is 90%. “Percent” means how many out of 100. Imagine there are 1,000 people without cancer, and based on their age and other characteristics, you expect 900 of the 1,000 to be alive in 5 years. Imagine that there are another 1,000 people similar in age and other characteristics as the first 1,000, but they all have the same specific type of cancer that has a 5-year survival rate of 90%. This means it is expected that 810 of the people with the specific cancer (90% of 900) will be alive in 5 years.

It is important to remember that statistics on the survival rates for people with metastatic breast cancer are only an estimate. They cannot tell an individual person if cancer will or will not shorten their life. Instead, these statistics describe trends in groups of people previously diagnosed with the same disease, including specific stages of the disease.

The 5-year relative survival rate for women with metastatic breast cancer in the U.S. is 30%. The 5-year survival rate for men with metastatic breast cancer is 19%.

The survival rates for metastatic breast cancer vary based on several factors. These include the stage of cancer, a person’s age and general health, and how well the treatment plan works.

It is important to remember that breast cancer is treatable at any stage. Treatments for metastatic breast cancer are continually improving and have been proven to help people with metastatic breast cancer live longer with a better quality of life.

Experts measure relative survival rate statistics for metastatic breast cancer every 5 years. This means the estimate may not reflect the results of advancements in how metastatic breast cancer is diagnosed or treated from the last 5 years. Talk with your doctor if you have any questions about this information. Learn more about understanding statistics.

Breast Cancer: Metastatic Risk Factors

What are the risk factors for metastatic breast cancer?

A risk factor is anything that increases a person’s chance of developing cancer or having it come back after it is first treated. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several known risk factors never develop cancer, while others with no known risk factors do. Knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices.

Risk factors for breast cancer

Most people who develop breast cancer of any stage have no obvious risk factors and no family history of breast cancer. But multiple factors may raise a person’s risk of developing the disease. Visit the Risk Factors and Prevention section of the earlier-stage Breast Cancer guide to learn about them.

Risk factors for metastatic breast cancer

Any type of breast cancer can metastasize. It is not possible to predict which breast cancers will metastasize. Whether metastasis happens depends on several factors, including:

• The type of breast cancer, such as hormone receptor-positive and/or HER2-positive, or triple-negative breast cancer (see Introduction)
• How cancer grows. For example, is it a faster-growing cancer or a slower-growing cancer?
• The stage of the cancer when it was first diagnosed, including the tumor size and whether cancer was found in nearby lymph nodes

There is no proven way to completely avoid developing metastatic breast cancer. Research continues to evaluate why metastatic breast cancer occurs and how to prevent, slow, or stop the growth of metastatic cancer cells.

Breast Cancer: Metastatic Symptoms and Signs

What are the symptoms and signs of metastatic breast cancer?

The symptoms and signs that people with metastatic breast cancer may experience depend on where and how much the cancer has spread. Symptoms are changes that you can feel in your body. Signs are changes in something measured, like taking your blood pressure or doing a lab test. Together, symptoms and signs can help describe a medical problem. Sometimes, people with metastatic breast cancer do not have any of the symptoms and signs described below. Or, often, the cause of a symptom or sign may be a medical condition that is not cancer.

The following signs or symptoms should be discussed with a doctor:.

Bone metastasis symptoms

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

Brain metastasis symptoms

• Headache
• Nausea and vomiting
• Seizures
• Dizziness
• Confusion
• Vision changes, such as double vision or loss of vision
• Personality changes
• Loss of balance

Lung metastasis symptoms

• Shortness of breath
• Difficulty breathing
• Constant dry cough

Liver metastasis symptoms

• Yellowing of the skin and whites of the eyes, called jaundice
• Itchy skin or rash
• Pain or swelling in the belly
• Loss of appetite
• Nausea

Other symptoms and signs of metastasis

• Loss of appetite
• Weight loss
• Nausea
• Vomiting
• Fatigue

If you are concerned about any changes you experience, please talk with your doctor. Your doctor will try to understand what is causing your symptom(s). They may do an exam and order tests to understand the cause of the problem, which is called a diagnosis.

If the doctor diagnoses metastatic breast cancer, relieving symptoms remains an important part of care and treatment. Managing symptoms may also be called “palliative and supportive care,” which is not the same as hospice care given at the end of life. You can receive palliative and supportive care at any time during cancer treatment. This type of care focuses on managing symptoms and supporting people who face serious illnesses, such as cancer. Learn more in this guide’s section on Coping with Treatment.

Be sure to talk with your health care team about the symptoms you experience, including any new symptoms or a change in symptoms.

Breast Cancer: Metastatic Diagnosis

If metastatic breast cancer develops, it may or may not cause symptoms. Sometimes these symptoms may lead a doctor to perform tests to find metastatic breast cancer or learn if an earlier breast cancer has metastasized. Testing to look for metastatic disease may also be performed if a patient is diagnosed with locally advanced breast cancer but doesn’t have any symptoms. You can find information on diagnosing breast cancer in the Diagnosis section of the earlier-stage Breast Cancer guide. Testing can also be helpful to learn the status of the disease. Doctors may also do tests to learn which treatments could work best.

How metastatic breast cancer is diagnosed

Your doctor may consider these factors when choosing a diagnostic test:

• Your medical history
• Your symptoms
• Your physical examination results

There are different tests used for diagnosing metastatic breast cancer. Your doctor may recommend the following tests to diagnose metastatic breast cancer:. Not all the tests described here will be used for every person.

• X-ray. An x-ray creates a picture of the structures inside of the body using a small amount of radiation. A chest x-ray may be used to look for cancer that has spread from the breast to the lungs.
• Bone scan. A bone scan may be used to look for the spread of cancer to the bones. The scan looks at the inside of the bones using a radioactive tracer. The amount of radiation in the tracer is too low to be harmful. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image. Some cancers do not cause the same healing response and will not show up on the bone scan. Areas of advanced arthritis or healing after a fracture will also appear dark.
• Computed tomography (CT or CAT) scan. A CT scan may be used to look for tumors in organs outside of the breast, such as the lung, liver, bone, and lymph nodes. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail in the image. The dye can be injected into a patient’s vein and/or given as a liquid to swallow.
• Positron emission tomography (PET) or PET-CT scan. A PET scan is a way to create pictures of organs and tissues inside the body. A PET-CT scan may also be used to find out whether the cancer has spread to organs outside of the breast. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A small amount of a radioactive sugar substance is injected into the patient’s veins. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body.
  
  Areas that are most active appear as bright spots, and the intensity of the brightness can be measured to better describe these areas. A PET-CT scan may also be used to measure the size of the tumors and to determine the location of the bright spots more accurately. A PET-CT scan will also show any abnormalities in the bone, similar to a bone scan (see above).
• Magnetic resonance imaging (MRI). An MRI produces detailed images of the inside of the body using magnetic fields, not x-rays. An MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye is usually injected into a patient’s vein.
• Serum chemistry and blood tests. These tests are often done to look at minerals in your blood, such as potassium and calcium. They also look at specialized proteins called enzymes that can be abnormal if cancer has spread. These tests can also evaluate how well the liver and kidneys are working. Although these test results can be abnormal if cancer has spread in the body, many noncancerous conditions can also cause changes in test results.
• Complete blood count (CBC). A complete blood count (CBC) measures the number of different types of cells, such as red blood cells and white blood cells, by testing a sample of a person’s blood. It is done to make sure that your bone marrow is working well.
• Blood tumor marker tests. Serum tumor markers, or biomarkers, are tumor proteins found in a person’s blood. They are made by the tumor or by the body in response to the cancer. Higher levels of a serum tumor marker may be due to cancer or a noncancerous condition. For metastatic breast cancer, testing may be done for cancer antigen 15-3 (CA 15-3), cancer antigen 27.29 (CA 27.29), and/or carcinoembryonic antigen (CEA). These biomarkers may be found in the blood of people with breast cancer. However, abnormal levels of these biomarkers may also be a sign of another condition that is not cancer. Some tests may also be done for circulating DNA or circulating tumor cells.
  Tumor marker testing may be useful to monitor the growth of recurrent or metastatic disease along with symptoms and imaging tests. The actual level of a tumor marker at any single time is less important than the changes in the levels over time. Decreasing levels of tumor markers usually mean that the treatment is working to shrink the cancer. Tumor markers should not be used to monitor for development of metastatic disease, as such testing does not appear to improve a patient’s chance of recovery. Treatment options and changes to treatment are primarily based on factors other than biomarkers, such as how much and where the tumor has grown and your overall health and treatment preferences.

Analyzing the cancer

One of the most important tests when someone is diagnosed with metastatic breast cancer is a tumor biopsy. A biopsy is the only way to make a definite diagnosis, even if other tests can suggest that cancer is present. During a biopsy, a small amount of tissue is removed for examination under a microscope. A biopsy can be done from many parts of the body, including lymph nodes, lungs, liver, bone, skin, or body fluids. The procedure is usually performed with guidance from a CT scan or ultrasound. Pain medication is used during this procedure to lessen discomfort. A pathologist will analyze the tissue sample. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

If you are diagnosed with metastatic breast cancer, your doctor may perform a biopsy to evaluate the features of the cancer and find out if they have changed in any way if you had an earlier diagnosis of breast cancer. These results are very important. Testing helps to determine the subtype of breast cancer, which is used to choose treatment options.

Standard testing of metastatic breast cancer looks at 3 important receptors:

• Estrogen receptors (ER) and progesterone receptors (PR). Generally, hormonal therapy (see Types of Treatment) is an option for ER-positive and/or PR-positive cancers. (Learn about ER and PR testing recommendations from the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) in a separate article on this website.)
• HER2. The HER2 status helps determine whether drugs that target the HER2 receptor might help treat the cancer. ASCO and CAP recommend that HER2 testing be done again if the cancer has spread to another part of your body or has come back after treatment, especially if results would influence your treatment options.

Additional testing may also be done. For example, testing the tumor DNA may find mutations in the cancer’s genes. This can help the doctor determine how the cancer will behave and identify potential treatment options. The following testing may be done to look at cancer genes:

• Genomic testing. Genomics is the study of the genes in a cancer cell. Genomic tests look at the genes in breast cancer to help determine what is causing the cancer to grow. The information from these tests can help the cancer care team understand how the cancer may behave and guide treatment decisions.
• Biomarker testing of the tumor. Your doctor may recommend running other laboratory tests on a tumor sample to identify specific gene changes, proteins, and other factors unique to the tumor. This may also be called molecular testing of the tumor. If you have locally advanced or metastatic breast cancer, your doctor may recommend testing for the following molecular features:
  • PD-L1. This protein can be found on the surface of cancer cells and some of the body’s immune cells. It stops the body’s immune cells from destroying the cancer.
  • Microsatellite instability-high (MSI-H) or DNA mismatch repair deficiency (dMMR). Tumors that are MSI-H or have a dMMR have difficulty repairing damage to their DNA. This means that they develop many mutations or changes. These changes produce abnormal proteins on the tumor cells that make it easier for immune cells to find and attack the tumor.
  • NTRK gene fusions. This is a specific genetic change found in many cancers, including some breast cancers.
  • PIK3CA. This genetic mutation is common in metastatic breast cancer.
• Genetic testing. Genetic testing looks at the genes inherited from a person’s parents. Genetic testing may be recommended if you have a family history of breast cancer or if you have a specific type of breast cancer, such as triple negative. Results from genetic testing may be used to identify treatment options, especially for people who have mutations in BRCA1 or BRCA2. In addition, finding out whether you have a genetic change linked with an increased risk of breast cancer may be important to other members of your family who could also have the genetic change. Learn more about inherited breast cancer risk.

After the diagnostic tests are done, your doctor will review the results with you. You will find out more about the cancer, its location, and the tumor subtype.

For many patients, a diagnosis of metastatic breast cancer comes as a shock. People describe a range of emotions, such as fear, anger, or sadness, that may change day-to-day or over time. You may have concerns about how this diagnosis will affect many different aspects of your life, such as your relationships, work or career, family and social roles, and finances. You may be worried about suffering or having your life shortened by this disease. It is important to remember you are not alone.

Patients and their families are encouraged to talk about the way they are feeling with doctors, nurses, social workers, or other members of the health care team. It may also be helpful to talk with other people with metastatic breast cancer, such as through 

How metastatic breast cancer is treated

In cancer care, different types of doctors who specialize in cancer, called oncologists, often work together to create a patient’s overall treatment plan that combines different types of treatments. This is called a multidisciplinary team. Breast cancer multidisciplinary care teams typically include medical oncologists, surgical oncologists, radiation oncologists, radiologists, and pathologists. In addition, cancer care teams include other health care professionals, such as physician assistants, nurse practitioners, oncology nurses, genetic counselors, social workers, pharmacists, counselors, dietitians, physical therapists, occupational therapists, financial advisors, and other supportive care members. Ask the doctor in charge of your treatment which health care professionals will be part of your treatment team and what they do. This can change over time as your health care needs change. Learn more about the clinicians who provide cancer care.

A treatment plan is a summary of your cancer and the planned treatment. It is meant to give basic information about your medical history to any doctors who will care for you during your lifetime. Before treatment begins, ask your doctor for a copy of your treatment plan. The treatment plan can be updated over time as your treatments change.

The main goals of metastatic breast cancer treatment are to make sure that you have the following:

• longest survival possible with the disease
• fewest possible side effects from cancer and its treatment
• best and longest quality of life possible

There is no cure for metastatic breast cancer, but a good quality of life is possible for months or even years.

Treatment options for metastatic breast cancer vary based on:

• Where in the body the cancer has spread?
• The presence and level of hormone receptors and HER2 in the tumor
• Gene mutations in the tumor
• Specific symptoms
• Previous cancer treatments
• Your overall health

How well treatment works depends on many factors as well, including the type of breast cancer, how widespread the cancer is, and what treatments have already been used. Because it is not unusual for metastatic breast cancer to stop responding to drugs over time, you may need to change treatments fairly often.

Take time to learn about all of your treatment options, and be sure to ask questions about things that are unclear. Talk with your doctor about the goals of each treatment and what you can expect while receiving the treatment. These types of conversations are called “shared decision-making.” Shared decision-making is when you and your doctors work together to choose treatments that fit the goals of your care. Shared decision-making is important for metastatic breast cancer because there are different treatment options. Learn more about making treatment decisions.

After testing is done, you and your doctor will talk about your treatment options. Your treatment plan may include certain treatments described below, but they may be used in a different combination or at a different pace. Your care plan also includes treatment for symptoms and side effects, an important part of cancer care.

READ MORE BELOW

• Hormonal therapy
• Chemotherapy
• Targeted therapy
• Immunotherapy
• Radiation therapy
• Surgery
• Summary of treatment options for metastatic breast cancer

Therapies using medication

The treatment plan may include medications to destroy cancer cells. Medication may be given through the bloodstream to reach cancer cells throughout the body. When a drug is given this way, it is called systemic therapy.

This treatment is generally prescribed by a medical oncologist, a doctor who specializes in treating cancer with medication.

Medications are often given through an intravenous (IV) tube placed into a vein using a needle or as a pill or capsule that is swallowed orally. If you are given oral medications to take at home, be sure to ask your health care team about how to safely store and handle them.

The types of medications used for metastatic breast cancer include:

• Hormonal therapy
• Chemotherapy
• Targeted therapy
• Immunotherapy

Each of these types of therapies are discussed below in more detail. A person may receive 1 type of medication at a time or a combination of medications given at the same time. The first set of drugs used for metastatic disease is called first-line treatment. If the cancer worsens, another combination of drugs may be used, called second-line treatment. These therapies can also be given as part of a treatment plan that includes surgery and/or radiation therapy.

The medications used to treat cancer are continually being evaluated. Talking with your doctor is often the best way to learn about the medications prescribed for you, their purpose, and their potential side effects or interactions with other medications. It is also important to let your doctor know if you are taking any other prescription or over-the-counter medications or supplements. Herbs, supplements, and other drugs can interact with cancer medications, causing unwanted side effects or reduced effectiveness.