Metastatic breast cancer (MBC) occurs when breast cancer spreads outside of the breasts to another part of the body, such as the liver.

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Approximately 30% of people who receive a diagnosis of early stage breast cancer will go on to develop metastatic, or stage 4, breast cancer. The liver is the third most common organ for breast cancer metastasis.

This article will explain what to expect when breast cancer spreads to the liver.

MBC is a late stage of cancer that starts in a person’s breast tissue. When breast cancer metastasizes, it means that its tissue spreads to distant organs, such as the liver, brain, or bones.

When MBC spreads to another organ, such as the liver, the diagnosis is still breast cancer.

Metavivor, an organization dedicated to researching MBC, states that 1 in 8 women will develop breast cancer during their lifetime. Of those, about 1 in 3 will experience metastasis.

For men, about 1 out of 1,000 will develop breast cancer during their life, but under 2% will experience metastasis.

The liver is the third most common area that MBC affects. Researchers are still not certain exactly how breast cancer spreads to the liver.

The current hypothesis indicates that it spreads to the liver when the cancer cells and liver are compatible. This is known as the seed and soil hypothesis.

According to research from 2015, the exact mechanics of how breast cancer spreads to the liver are still not known.

However, in one 2019 study, researchers found that a few distinguishing factors may place a person at higher risk of developing liver metastasis. These include:

  • age
  • menopausal status
  • number of lymph node metastases
  • tumor size

Earlier or more frequent screening for liver metastasis may help improve outlook because a doctor may find the tumor sooner.

Breast cancer that spreads to the liver does not usually cause any symptoms.

A doctor is more likely to find the cancer on a liver function test. The liver function test uses a blood sample to determine the level of liver enzymes and proteins in the blood.

If liver metastasis does cause symptoms, they can include:

  • fever
  • poor appetite
  • bloating
  • fatigue or weakness
  • discomfort or pain in the mid-section
  • weight loss
  • jaundice, or a yellowing of the skin or whites of the eyes
  • swelling in the legs

There is currently no cure for MBC, so treatment usually focuses on slowing the growth of the tumor and improving a person’s quality of life. Treatment can also help increase the person’s lifespan.

Treatment for MBC may not be as aggressive as it is in the earlier stages of breast cancer. In the earlier stages of breast cancer, doctors try to remove or destroy the cancer altogether.

If it metastasizes, doctors use medication to help control the cancer and slow its growth, which increases life expectancy.

According to the American Cancer Society, systematic medications are the main treatment for MBC. These include:

  • immunotherapy
  • chemotherapy
  • hormone therapy
  • targeted drugs

A doctor may suggest a combination of these therapies. They may also recommend radiation therapy or surgery in some situations.

People with MBC should discuss with a doctor what treatments may be best for them. Some factors to consider include:

  • the symptoms present
  • the size of the tumor in the liver
  • past treatments
  • whether or not the cancer has spread to other organs
  • the person’s general health
  • their age or menopause status
  • features of the cancer

Someone with MBC that has spread to the liver may live for several more years with successful treatment.

According to some research, the 5-year survival rate is about 23% for MBC. However, without treatment, breast cancer that metastasizes to the liver can cause a person’s survival time to drop to around 4–8 months.

Since there is currently no cure, treatment tends to focus on slowing the growth and spread as well as managing the symptoms.

A person may decide, based on their age or overall health, to discontinue treatment. In these cases, the person should talk with a treatment team and their family about end-of-life care.

With treatment, a person may be able to live for several years. The person should talk with a doctor about their individual outlook, as several factors can affect successful treatment.

MBC that spreads to the liver currently has no cure.

With treatment, a person may be able to slow down the growth of the tumor and improve their quality of life. The person should talk with a doctor about the best treatment options for them.