Metastatic breast cancer, also known as stage 4 cancer, refers to breast cancer that has spread to other parts of the body. It typically spreads to the brain, bones, lungs, and liver.

In this article, we discuss the symptoms, diagnosis, and treatment for metastatic breast cancer.

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Metastatic breast cancer – also called stage 4, secondary, or late-stage breast cancer – is breast cancer that has spread to another part of the body.

Nearly 30% of women diagnosed with early-stage breast cancer develop metastatic disease.

Men can also be diagnosed with metastatic breast cancer. This is rare, though. Less than 1% of all breast cancer cases develop in men, and only one in a thousand men will be diagnosed with male breast cancer. Of these cases, only about 2% will metastasize.

Symptoms of metastatic breast cancer can vary depending on the organs that the cancer has started to affect. Here are some common signs of metastatic breast cancer to look out for:

Learning to recognize these symptoms and getting a diagnosis early on can ensure that a person receives the right treatment promptly. This can improve both the quality and length of a person’s life.

Cancer spreads when cancerous cells grow and move beyond their original location. This usually happens through one or more of the following steps:

  • Cancer cells invade nearby healthy cells. When the healthy cell is taken over, it too can start making more bad cells.
  • Cancer cells penetrate into the circulatory or lymph system. Cancer cells travel through the walls of nearby lymph vessels or blood vessels.
  • Migration through circulation. Cancer cells use the lymph system and/or the bloodstream as pathways to travel to different parts of the body.
  • Cancer cells lodge in capillaries. Cancer cells stop moving as they are lodged in tiny blood vessels called capillaries. There, they stop moving, multiply, and spread into the nearby tissue.
  • New small tumors grow. Cancer cells form small tumors at the new location elsewhere in the body (called micrometastases).

The most common parts of the body where breast cancer tends to spread are the brain, bones, lungs, and liver.

It can develop when initial cancer treatment has not been effective.

Breast cancer can also become metastatic if it was already advanced by the time a person received a diagnosis, for example, because the cancer was aggressive or caused no noticeable symptoms.

If a person has a history of breast cancer and develops any symptoms of metastatic breast cancer, a doctor may recommend one or more of the following tests to make a diagnosis:

There are several ways to treat metastatic breast cancer. Options depend on the type of breast cancer, including whether hormonal factors play a role.

Some treatments, such as chemotherapy, can stop the cancer from spreading further. Other treatments that aim to stop or slow cancer’s progression include:

Hormone therapy: This can help if breast cancer involves certain hormonal features.

Targeted therapy: This can affect the way that changes in specific genes, such as BRCA1 or BRCA2, affect the growth of cancer cells.

Chemotherapy: This aims to kill cancerous cells throughout the body.

Radiation therapy: This can reduce the size of tumors and help relieve symptoms.

Surgery: This is not usually an option for metastatic breast cancer, but it may be appropriate in some cases.

Other options include:

  • bone strengthening therapy, which can help keep the bones strong
  • pain relief medication
  • treatment to help with other effects of cancer, such as anxiety and depression

All of these treatments can have adverse effects, such as nausea and fatigue.

A doctor can often suggest ways to limit the impact of symptoms and side effects of medication. Anyone experiencing severe discomfort or concerns should speak to a doctor.

If a person has early-stage cancer, which refers to cancer that has not spread, they will stop treatment when the cancer cells are gone. When cancer is metastatic, however, treatment will be ongoing.

Proton therapy is an emerging treatment for cancer. Learn more here.

Palliative care

Palliative care is specialized medical care for people living with a serious illness, such as metastatic breast cancer. It is intended to help people manage their symptoms and preserve their quality of life.

Palliative care includes:

  • medications to reduce pain and discomfort
  • physical therapy
  • treatment for any anxiety or depression
  • counseling to help with personal, social, and spiritual concerns

Many people benefit from a combination of these forms of care.

In addition, complementary treatments may help, including:

Hospice care

A person with metastatic breast cancer may require hospice care, either in a special facility or at home, when their life expectancy is 6 months or less. Hospice care aims to help the person live as comfortably as possible through the end of life.

What does a person experience during end-stage breast cancer? Learn more here.

Living with advanced-stage cancer can be difficult for the individual, their family, and their friends. The American Cancer Society recommends the following strategies for coping:

  • learn as much as you can about the condition and what to expect
  • understand that it is not possible to control every aspect of cancer
  • learn ways to let go of feelings and fears, for example, by talking about them
  • eat healthfully and exercise when you can
  • find ways to relax and do things that bring pleasure
  • participate in support groups as much as possible

Monitoring, or follow-up care, is extremely important. It allows a doctor to check whether the cancer has spread further. It can also help with managing side effects and assessing overall health.

The doctor will ask about symptoms and general well-being. They may perform a physical examination, and they will likely check measures of the person’s overall health.

The doctor may recommend further scans and blood tests. Depending on the results, they may adjust the treatment plan.

A person should inform their doctor right away about any new health problems.

Below are some commonly asked questions about metastatic breast cancer.

What is the first red flag of metastatic breast cancer?

Feeling constantly tired, nauseous, and unexplained weight loss are red flags that a person’s breast cancer may have spread or metastasized.

Where is the first place metastatic breast cancer usually spreads?

The first place metastatic breast cancer usually spreads is to the lungs, bones, liver, or brain.

The outlook depends on the type of breast cancer, the extent of the spread, and how the cancer is affecting these areas.

Based on past statistics, the average life expectancy for a person with metastatic breast cancer is 18–24 months. However, this can vary widely. In addition, past statistics do not reflect more recent advances in treatment.

As the American Cancer Society notes, 30% of people with this diagnosis will live another 5 years or more.

Many people with metastatic breast cancer live long and productive lives, and treatment can often control the cancer.

Survival rates vary, depending on the individual. Speak to the doctor to get a better understanding of specific circumstances.