Where Does Breast Cancer Spread?

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Breast cancer is cancer that begins in the breast. According to the , breast cancer is the most common cancer in women in the United States, making up about 30 percent of all new cancer diagnoses in women.

While breast cancer begins in the breast, it can also spread to other areas. When a cancer spreads to more distant tissues from where it started, it’s called metastatic cancer. Research estimated that were living with metastatic breast cancer in the United States in 2017.

Below, we’ll explore more about metastatic breast cancer and the most common areas where it’s detected. Then, we’ll cover how this type of cancer is diagnosed and treated, plus steps you can take to prevent it.

What is metastatic cancer?

Metastatic cancer is cancer that’s spread to a different part of the body than where it originated. You may also see metastatic cancer referred to as .

In some cases, the cancer may have already spread by the time of initial diagnosis. Other times, the cancer may spread after the initial treatment. For example, a person who has been treated for early-stage breast cancer may later be diagnosed with metastatic breast cancer.

Metastasis can occur with almost every type of cancer and is considered advanced-stage cancer. Cancer metastasis may occur months to years after initial breast cancer treatment.

There’s also a type of metastatic cancer called oligometastatic cancer. This is where there’s only a few small areas of metastatic cancer. Because this type of metastatic cancer is only found in a few locations, researchers hope it will be .

What’s the difference between metastatic and recurring breast cancer?

is cancer that comes back after your initial treatment. This can happen when treatment doesn’t completely destroy all of the cancer cells in a tumor. As time passes, these remaining cancer cells can begin to grow into detectable tumors.

Like metastasis, recurrence can happen with almost every type of cancer. As we’ll see below, some types of recurrent cancer can happen distantly and therefore also fall under the umbrella of metastatic cancer.

may recur locally, regionally, or distantly:

  • Local recurring breast cancer occurs when a new tumor develops in the breast that was originally affected. If the breast has been removed, the tumor may grow in the chest wall or nearby skin.
  • Regional recurring breast cancer happens in the same region as the original cancer. In the case of breast cancer, this may be the lymph nodes above the collarbone or in the armpit.
  • Distant recurring breast cancer happens when cancer cells travel to a different part of the body. This new location is far away from the original cancer. When cancer recurs distantly, it’s considered metastatic cancer.

Where are the common sites that breast cancer metastasizes to?

According to the , the most common metastasis locations for breast cancer are the:

  • bones
  • lungs
  • liver
  • brain

The frequency that breast cancer metastasizes to each of these sites can vary based off of the population studied. A in Scientific Reports included a group of 4,932 people with metastatic breast cancer. Researchers determined the metastatic site (or sites) for each person and found that:

  • 65.1 percent of people had bone metastases
  • 31.4 percent of people had lung metastases
  • 26 percent of people had liver metastases
  • 8.8 percent of people had brain metastases

Additionally, 33.5 percent of people had metastasis in multiple organs. The most common combination of sites were the bones and lungs.

Bone metastasis

Bones are often the first site that breast cancer metastasizes to. Any bone can be affected, although the most common ones include the:

  • spine
  • pelvis
  • ribs
  • long bones in the arms and legs

Initially, it can be hard to tell the difference between a and the effects of much more common conditions like or a . However, pain from a bone metastasis eventually becomes persistent and doesn’t go away with rest.

Lung metastasis

It’s possible to have a and not know it, as symptoms aren’t always present. In fact, your doctor may first find a lung metastasis during a follow-up scan after your initial treatment.

When symptoms are present, it’s easy to initially mistake them from those of a pre-existing lung condition or a respiratory infection like the or . However, symptoms will continue to linger long after a respiratory infection should have cleared.

Liver metastasis

Similar to a lung metastasis, breast cancer that’s spread to the liver may not cause noticeable symptoms at first. Because of this, it may first be detected when routine blood tests show , which can be a sign of liver damage.

Brain metastasis

In many people with a brain metastasis, breast cancer has already spread to other areas of the body. According to this , the spread of breast cancer to the brain is more common with aggressive types of breast cancer like or breast cancer.

Other, less common areas breast cancer may spread to

Breast cancer metastasis isn’t just limited to the sites we’ve listed above. Breast cancer can also spread to other areas of the body, although this is much less common. Some examples the:

  • female reproductive tract, like the ovaries, cervix, and endometrium
  • digestive tract, such as the esophagus, stomach, and
  • kidneys
  • eye

What are the symptoms of metastatic breast cancer?

As mentioned earlier, not everyone with metastatic breast cancer experiences . When symptoms do occur, they can vary and depend on the location of the metastasis and its severity. Let’s look at the symptoms for each common metastatic site now.

Bone metastasis symptoms

Metastasis to the bones may cause:

  • severe
  • bones that are more brittle and can break easily
  • , which can lead to:
    • pain in your back or neck
    • weakness or numbness in a particular area
    • trouble urinating or having a bowel movement
  • low blood cell counts, which can cause symptoms like:
    • easy or bleeding
    • frequent

As bone tissue continues to be damaged, calcium can be released into the blood, leading to a condition called , which causes symptoms like:

  • fatigue
  • nausea
  • increased thirst
  • constipation
  • irritability
  • confusion

Lung metastasis symptoms

Metastasis to the lungs may cause:

Liver metastasis symptoms

Metastasis to the liver may cause:

  • , or yellowing of the skin and the whites of the eyes
  • fatigue

Brain metastasis symptoms

Metastasis to the brain may cause:

  • nausea or vomiting
  • weakness or numbness
  • changes in or behavior
  • or difficulty speaking
  • changes in vision like or

Symptoms that may accompany any form of metastatic breast cancer

Nonspecific symptoms that may accompany any form of metastatic breast cancer include:

  • fatigue
  • a general feeling of unwellness ()
  • loss of appetite

Some symptoms may not be caused by the cancer itself, but by the treatment that you’re undergoing. If you’re experiencing any of these symptoms, speak with your doctor. They may be able to recommend a therapy to alleviate some symptoms.

What causes metastatic breast cancer and who’s at risk?

Metastatic breast cancer happens when cancer cells break away from the original tumor site. These cells then make their way to other parts of the body via the or lymphatic systems.

Once the cells settle somewhere in the body, they have the potential to form a new tumor. This can happen quickly or develop years after initial treatment.

Anyone that’s been diagnosed with breast cancer can go on to develop metastatic breast cancer. Generally speaking, some of the factors below may increase the likelihood of breast cancer metastasizing:

  • having a more aggressive type of breast cancer like
  • being diagnosed with breast cancer that’s at a , such as cancer that’s already spread to nearby lymph nodes or the chest wall
  • having a cancer that’s growing quickly

How is metastatic breast cancer diagnosed?

Several tests are used to confirm a diagnosis of metastatic breast cancer. These include:

  • Blood tests: In these tests, a sample of blood is taken from a vein in your arm. Some common blood tests that may be ordered include a and a . Your doctor may also order tests for .
  • Imaging tests: Imaging tests allow your doctor to see what’s going on inside of your body and check for the presence of suspicious areas. Some examples of imaging tests that may be used include:
  • Tissue biopsy: If imaging shows a suspicious area, your doctor will take a from that area to be analyzed in a laboratory. The results of a tissue biopsy can confirm a diagnosis of metastatic breast cancer.

The tests that are used as a part of the diagnostic process can vary based on where the cancer has spread to. For example, imaging like a bone scan would be used to check for a bone metastasis while a would be used to check for a brain metastasis.

Similarly, additional tests may be used as well, based off of the site. An example of this is to check for signs of cancer in the airways when a lung metastasis is suspected.

How is metastatic breast cancer treated?

There isn’t a cure for metastatic breast cancer. However, there are treatments aimed at preventing further progression, reducing symptoms, and improving the quality and length of life.

Treatments are highly individualized. What’s recommended can depend on things like:

  • the location and extent of the metastasis
  • whether or not the cancer is positive for hormone receptors (HR) or
  • whether or not certain genetic changes are present
  • which treatments you’ve previously received
  • your age and overall health
  • your personal preference

Potential treatment options for metastatic breast cancer include:

Hormone therapy

If the cancer is positive for hormone receptors ( or ), hormone therapy may be recommended. This prevents hormones from acting on these cancer cells, thereby slowing or stopping their growth.

Drugs that are used for include and aromatase inhibitors like:

  • anastrozole ()
  • exemestane ()
  • letrozole ()

Sometimes, hormone therapy will also be combined with a targeted therapy drug.

Chemotherapy

If the cancer is negative for hormone receptors or hasn’t responded to hormone therapy, may be recommended. This treatment uses drugs that kill cancer cells or slow their growth.

Chemotherapy can also be combined with other treatments, such as targeted therapy and immunotherapy. For example, if the cancer is HR-negative and HER2-positive, chemotherapy may be combined with targeted therapy drugs that target the HER2 protein.

Targeted therapy

uses drugs that target specific proteins that are on or inside of breast cancer cells. There are many types of targeted therapy drugs:

  • drugs for HER2-positive cancers, including but not limited to:
    • trastuzumab ()
    • pertuzumab ()
    • lapatinib (Tykerb)
    • tucatinib (Tukysa)
    • ado-trastuzumab emtansine (Kadcyla), a targeted therapy drug linked to a chemotherapy drug
  • drugs for HR-positive cancers like:
    • palbociclib ()
    • ribociclib ()
    • abemaciclib ()
    • everolimus ()
    • alpelisib ()
  • drugs that target cancers with mutations in like olaparib () and talazoparib ()

Additionally, the drug sacituzumab-govitecan () may be used for triple-negative breast cancer. This treatment is a targeted therapy drug that’s linked to a chemotherapy drug.

Immunotherapy

is a type of cancer treatment that helps your immune system respond to cancer cells. An example of immunotherapy for metastatic breast cancer is pembrolizumab ().

Researchers continue to work on new immunotherapy approaches. For example, in February 2022, a clinical trial of a personalized immunotherapy treatment for metastatic breast cancer yielded . This treatment harnesses the power of tumor-fighting cells isolated from trial participants to help shrink tumors.

Other treatments

Generally speaking, the main treatments for metastatic breast cancer are the systemic treatments listed above. A systemic treatment impacts the entire body, as opposed to one location. However, other treatments can also be used for metastatic breast cancer as well.

For example, or surgery may be used to help with cancer that’s spread to specific areas. These include the:

  • bones
  • brain
  • spinal cord
  • chest wall

Bone-building drugs called can also be used to reduce bone pain and increase bone strength in people with bone metastasis.

Deciding which treatment is best for you

Deciding on the best treatment option for you requires both information and careful consideration. Although you should work with your doctor to understand your options, the choice is ultimately up to you. As you consider the possibilities, keep these tips in mind:

  • Don’t rush into anything: Take time to consider your choices, and get a second opinion if necessary.
  • Bring someone with you to your doctor appointments: Take notes or ask your doctor if you can record your visit. This can help ensure that you don’t forget anything that’s discussed.
  • Ask questions: Have your doctor explain all of the potential benefits, risks, and side effects associated with each treatment.
  • Consider a clinical trial: Find out if there are any for which you may be eligible. There may be an experimental treatment option available for your specific cancer.

Although receiving a metastatic breast cancer diagnosis can be overwhelming, there are many treatment options that can help reduce symptoms and prolong . Though there isn’t a current curative treatment, some women will live for many years with metastatic breast cancer.

Research on how to stop cancer cell growth, boost the immune system, and disrupt cancer metastasis is ongoing, and new treatment options may be available in the future.

Can you prevent or lower your risk for metastatic breast cancer?

There isn’t a definitive way to guarantee that your cancer won’t recur or metastasize after treatment, but there are steps you can take that may reduce your risk. These steps include:

  • Managing weight: If you have or are overweight, talk to your doctor about healthy ways to manage your weight. A notes that increases in associated with obesity may create an environment that promotes cancer growth and metastasis.
  • Staying active: Keeping active is great for your overall health. It may also recurrence and metastasis, perhaps due to the beneficial effect that physical activity can have on the immune system.
  • Eating a balanced diet: While we’re still learning more about diet and breast cancer, a suggests that excess intake of fats and carbs may impact the development of metastatic breast cancer. To eat a , aim to do the following:
    • eat more fresh fruits and vegetables, whole grains, legumes, poultry, and fish
    • lower your consumption of red or processed meats
    • avoid sugar-laden foods
  • Cutting back on alcohol: Drink in moderation or not at all. Moderate drinking is one drink per day for women and two drinks per day for men. is a risk factor for developing breast cancer, but its impact on cancer metastasis or recurrence is still .

Takeaway

Metastatic cancer happens when cancer spreads to more distant areas of the body. The most common locations that breast cancer metastasizes to are the bones, lungs, liver, and brain.

The symptoms of metastatic breast cancer depend on which part of the body is affected. A doctor will use blood tests, imaging tests, and tissue biopsies to help make a diagnosis.

While metastatic breast cancer doesn’t currently have a cure, there are treatments available that can help to reduce the cancer and improve quality of life. Additionally, researchers continue to develop newer, more effective treatments for metastatic breast cancer.