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Understanding Metastatic Breast Cancer

What Is Metastatic Breast Cancer?

The terms “metastatic breast cancer” and “stage 4 breast cancer” both refer to cancer that has spread beyond the breast to other organs in the body. When breast cancer metastasizes, or spreads, it typically can be found in one or more of the following areas:

  • the lungs
  • the liver
  • the brain
  • the bones

Still, breast cancer can spread to any organ.

Although there aren’t stages within the metastatic breast cancer classification, there are factors that can affect your treatment, outlook, and quality of life.

This form of cancer can be difficult to treat. There isn’t a cure, but continuing advancements in treatment are improving the quality of life and extending life expectancies.

What Are the Symptoms of Metastatic Breast Cancer?


Breast cancer symptoms typically include a lump in the breast, in addition to:

  • pain
  • discomfort
  • swelling of the breast in the underarm region
  • changes in the skin, such as dimpling or ulceration
  • nipple discharge
  • large or hard lymph nodes under your arm, in your armpit, or in your neck

Advanced symptoms may include:

  • pain
  • shortness of breath
  • difficulty sleeping
  • difficulty digesting
  • fatigue

The signs differ depending on where the cancer has spread and how much it has advanced. For example, if the cancer metastasizes to your bones, you may start to experience pain in the affected area or areas. Bone metastases typically occur in the spine and long bones of the legs and arms.

Breast cancer that metastasizes to the liver may cause jaundice and abdominal pain. If the lungs are affected, you may experience a chronic cough and chest pain.

If the cancer has spread to the brain, you may notice changes in personality or an increase in headaches.

What Causes Metastatic Cancer?


Metastatic breast cancer is caused by the spread of cancer cells, which can occur in a number of ways.

Typically, the cells break off from the main tumor and travel through the bloodstream. Once these cells are in your bloodstream, they can spread anywhere in your body.

Some cells from the primary cancer can break away, travel to another part of the body, and start growing there in order to spread. Cancer cells don’t stick together as well as noncancerous cells do.

Cancer cells may also produce substances that stimulate them to move. If the cancer cells go into small blood vessels, they can get into the bloodstream. The circulating blood moves the cancer cells along until they get stuck somewhere, usually in a capillary.

Then, the cells move through the wall of the capillary and into the tissue of a nearby organ. If the conditions are right, the cells can multiply and form a new tumor.

Cancer cells may also break away and become stuck in one or more of the nearest lymph nodes. This is why doctors check the lymph nodes first when they’re figuring out how far a cancer has grown or spread.

How Is Metastatic Cancer Diagnosed?


Mammograms and ultrasounds, which are types of imaging tests, are the most common diagnostic tests for breast cancer.

Visual imaging tests, such as an MRI or CT scan, are used to detect the spread of cancer in places like your abdomen, back, and lungs. They may consider performing a bone scan if they suspect the cancer has spread to your bones.

Blood tests that look for markers of cancer can also be very useful. A physical exam and a detailed conversation about your symptoms may also expedite a diagnosis.

Read more: Metastatic breast cancer by the numbers: Facts and statistics »

How Is Metastatic Breast Cancer Treated?


Treatment options can vary depending on the type of metastasis involved and its location.

Systemic therapy can include some combination of:

  • chemotherapy
  • biologic therapy
  • targeted therapy
  • hormonal therapy

This approach is different from local therapy, which is a treatment that’s directed at a specific tumor.

Local therapy typically includes radiation therapy and surgery. A combination of local and systemic therapies may also be appropriate.

Chemotherapy and Radiation Therapy

Both chemotherapy and radiation therapy can be used to shrink tumors and slow down any further growth. Although these therapies may be able to target and treat the cancer cells, there can be various side effects that come alongside these particular treatments. Common side effects of chemotherapy and radiation are:

  • fatigue
  • pain
  • anemia
  • appetite loss
  • bleeding
  • bruising
  • constipation
  • diarrhea
  • hair loss
  • infection
  • neutropenia
  • lymphedema
  • memory problems
  • concentration problems
  • nausea
  • vomiting
  • neuropathy
  • skin changes
  • nail changes
  • insomnia
  • sexual problems
  • fertility problems

Hormone Therapy

Hormone therapy may be the first approach if the cancer is hormone receptor-positive. This therapy works by suppressing estrogen, which cancer cells need to grow in cancers that are hormone-positive.

Options such as tamoxifen (Nolvadex) attach to the estrogen receptors on cancer cells and prevent estrogen from reaching the receptor. Aromatase inhibitors stop the production of estrogen in postmenopausal women.

Metastatic breast cancer that’s estrogen receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative may benefit from the drug palbociclib (Ibrance).

Biologic Targeted Therapy

One of the most encouraging developments in treating metastatic breast cancer is the drug trastuzumab (Herceptin). This therapy binds to the HER2 gene receptors. This prevents the receptors from overproducing the problematic protein.

Herceptin can also block tumor cell growth and target the cancer cells for destruction.

Lapatinib (Tykerb) may be used if Herceptin is no longer working. It crosses the blood-brain barrier, so it’s also considered when the cancer has metastasized to the brain.

Research is also being done on the drug bevacizumab (Avastin), which is another drug used to treat metastatic disease.



Your first step should be to educate yourself about your diagnosis. Learn as much as you can about your particular tumor, and then explore your treatment options. Consider getting a second or even a third opinion.

Also, make sure you understand all of the risks and benefits of available treatments. If a particular treatment has serious side effects, talk with your oncology team and your loved ones about these decisions. Talk about the care you may need at home, the amount of time that you may need to be away from work, and how to arrange rides to the hospital for treatment and follow-up care.

Understand that while some treatments are designed to prolong life, other treatments may be focused on managing symptoms.

If you haven’t already done so, this may be a good time to reach out to other people with breast cancer and survivors of breast cancer to learn from their experiences. You can find a list of support groups in your area here.

The breast cancer community maintains a helpful and enthusiastic online presence. Healthcare providers and survivors often share their stories and information about new treatments. You can find an example of one of these blogs here.

Reducing Your Risk of Breast Cancer


Your age and sex are risk factors for breast cancer that you can’t control. You also can’t control your the medical history of your family, but it’s still important to understand your family history. It’s also important to share your own medical history with your doctor. This will to help you work with your doctor to make decisions that are right for you.

One way to help prevent breast cancer is to avoid smoking. If you smoke, talk to your doctor about products and therapies that can help you quit. You should also maintain a healthy weight because obesity raises your risk of breast cancer. Limiting alcohol to no more than one drink per day can also reduce your risk.

Breast cancer is becoming a highly treatable disease when caught early. Metastatic breast cancer remains a challenge, but the outlook for people with metastatic disease is continuing to improve as treatments and therapies become more targeted.

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