Metastatic, or stage 4, breast cancer is when the cancer has spread to another part of the body. It most commonly affects the bones, brain, liver, or lungs.

Metastatic cancer refers to cancer that has spread from the original tumor and nearby lymph nodes to other parts of the body. It is also referred to as stage 4 cancer, which is the most severe type of cancer.

Approximately 30% of people with early-stage breast cancer will eventually receive a diagnosis of metastatic breast cancer. This diagnosis can occur months or even decades after the initial breast cancer diagnosis.

Metastatic breast cancer is also referred to as advanced secondary breast cancer because when breast cancer spreads to other areas of the body, the cancer cells are still breast cancer cells.

For example, even if the cancer metastasizes in the bones, the tumor will consist of breast cancer cells, not bone cancer cells.

Both terms are used, however, advanced is more commonly discussed than secondary.

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According to the National Cancer Institute (NCI), breast cancer cells typically metastasize in a series of six steps:

  1. The cancer cells grow into or invade nearby healthy tissue.
  2. They penetrate the walls of nearby lymph nodes or blood vessels.
  3. They travel through the lymphatic system and bloodstream to other areas in the body.
  4. They invade blood vessel walls and move into surrounding healthy tissue at the new location.
  5. They grow in the new tissue until a small tumor forms.
  6. They develop new blood vessels to establish a blood supply for the tumor so that it continues to grow.

Some people may have metastatic breast cancer and not experience any symptoms. If symptoms do occur, they may vary based on the size of the tumors and where in the body they have spread.

Common signs and symptoms of metastatic cancer include:

Bones• bone pain and fractures commonly in the spine, pelvis, ribs, or the long bones in the arms or legs
Brain• dizziness
• headaches
• slurred speech
• seizures
• vision issues
• memory problems
Liver• abdominal swelling
• jaundice
• poor appetite
• fatigue
• weight loss
• fever
Lungs• shortness of breath
• persistent cough
• general chest discomfort or pain

A doctor may perform a variety of tests to identify and look for cancer spread throughout the body, including:

  • bone scans
  • chest X-rays
  • CT scans
  • MRI scans
  • PET or PET CT scans
  • blood tests
  • biopsy

There is currently no cure for metastatic breast cancer. However, treatment may help:

  • slow or stop the spread of the cancer
  • relieve the symptoms
  • improve quality of life
  • prolong life

Treatment for metastatic breast cancer is typically different than before the cancer has spread. That said, with treatment, a person can live for several months or years with metastatic breast cancer.

A person should work with a doctor to understand their treatment options, which may include:

  • chemotherapy to damage or destroy cancer cells throughout the body
  • radiation therapy to control cancer growth in specific areas and ease symptoms such as pain
  • targeted therapy, which targets specific receptors and abnormal growth pathways to help prevent growth
  • hormone therapy to help to shrink or slow the growth of hormone receptor-positive metastatic breast cancer
  • clinical trials, which test new medications or therapies aiming to improve cancer care

Complementary and holistic medicine such as hypnosis, acupuncture, and yoga, as well as palliative care, may be used at the same time as the options above.

Treatment will continue until a person is no longer benefiting from it.

The natural history of metastatic breast cancer is that a person’s cancer becomes resistant to a given therapy over time. At that point, a doctor should discuss other options and next steps with the person.

If treatments are no longer effective at slowing cancer spread or alleviating the symptoms, a doctor may recommend stopping treatment. These decisions are made between the oncology team, the person with metastatic cancer, and the family.

It is important for an individual to discuss how they are doing and what their goals are continually with their healthcare team and loved ones so everyone can understand their priorities.

Even when people decide to stop receiving chemotherapy or similar treatments, they can still receive palliative care and complementary therapies to support their quality of life and relieve them of symptoms.

The outlook for metastatic breast cancer is different for each person and will depend on a few factors, such as:

  • type of cancer
  • organs affected
  • a person’s general health status
  • level of fitness
  • previous treatments

A person’s outlook is typically estimated by using the 5-year relative survival rate.

This compares people with the same type of breast cancer to the general population to calculate how many people are still alive 5 years after their initial diagnosis.

The 5-year relative survival rate for metastatic breast cancer is 30%.

What is the most common route of metastasis for breast cancer?

Metastasis for breast cancer most commonly spreads to the bones, liver, brain, and lungs.

Where does breast cancer usually metastasize first?

Metastatic breast cancer most often affects the bones first.

How long after breast cancer can it metastasize?

How fast breast cancer will metastasize is hard to predict and varies for each person. Some people’s initial breast cancer diagnosis may indicate metastasis, while for others the cancer may metastasize decades after treatment or their initial diagnosis. Early detection of breast cancer can greatly decrease the risk of complications and metastasis.

Metastatic, or stage 4, breast cancer occurs when the cancer cells have spread to other areas in the body. It often affects the bones, brain, liver, and lungs.

There is currently no cure for metastatic breast cancer. Treatment focuses on slowing the growth and spread of the cancer as well as reducing the symptoms and improving a person’s quality of life.