Invasive breast cancers are types of cancers that are prone to spreading, either within the breast or beyond. Metastatic breast cancer is a specific stage of cancer indicating the spread to distant parts of the body.

Abnormal cells aren’t cancerous, but they may increase your risk of developing cancer. When you have abnormal cells that haven’t spread, the cells are considered noninvasive. This is sometimes referred to as pre-cancer or stage 0 cancer.

If abnormal cells move beyond the layer of tissue where they originated, the cells become invasive. When abnormal cells inside the milk ducts or lobules move out into nearby breast tissue, it’s considered a local invasion or invasive breast cancer.

These cells can also break free from the primary site and migrate to other parts of the body. When this happens, the cancer isn’t just invasive, it’s also metastatic.

Metastatic or stage 4 breast cancer is defined as cancer that has spread from the breast to distant parts of the body.

Learn more about the different stages of breast cancer here.

Key differences between invasive and metastatic breast cancer

Metastatic breast cancer isn’t a “type” of cancer. Rather, it’s a term used to describe a specific “stage” of cancer. Invasive breast cancer is a certain type of cancer.

Both metastatic and invasive breast cancers have spread beyond their points of origin.

Invasive breast cancers may have spread within the breast only, to nearby lymph nodes, or to distant parts of the body. Metastatic breast cancers have spread to distant areas in the body, such as the bones, lungs, liver, or brain.

Breast cancers that are invasive only in the breast are easier to treat than metastatic cancers that have spread to distant tissues or organs.

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There are two broad categories of breast cancer: invasive and noninvasive. Invasive cancers tend to be more aggressive and fast-growing, while noninvasive breast cancers tend to grow more slowly.

The two most common types of invasive breast cancer are invasive ductal carcinoma and invasive lobular carcinoma.

Invasive breast cancer means that the cancer cells have spread from their original site to nearby breast cancer tissue or lymph nodes. The cancer cells can also spread to other, more distant areas of the body via the bloodstream or lymphatic system (in lymph fluid).

Cancer that has spread from your breast to distant areas of your body is called “metastatic” breast cancer.

Metastatic breast cancer is defined as cancer that has spread from the primary site where it began to other parts of your body. It’s also commonly referred to as stage 4 breast cancer.

Metastatic breast cancer is most likely to spread to your bones, lungs, brain, or liver.

When cancer spreads to a new area in your body, it’s still considered to be breast cancer. For example, breast cancer that has spread to your lungs is called “metastatic breast cancer to the lungs.”

While there’s no cure for metastatic breast cancer, treatment can keep it under control for many years. The cancer may alternate between being active and going into remission. Remission is when the cancer cells are still in your body, but at levels too small to be detected in scans or other tests.

Metastatic cancer can be any type of breast cancer. Doctors use the term “metastatic breast cancer” to describe a stage of breast cancer where the cancer has spread from the breast to a distant part of your body.

Invasive breast cancer is a specific type of breast cancer that is more prone to spreading than other, more slow-growing types of breast cancer.

Symptoms of invasive breast cancer

Symptoms of invasive cancer depend on the type of invasive cancer you have and whether it has spread within your breast, to nearby lymph nodes, or to distant parts of your body.

Initial symptoms of invasive ductal carcinoma and invasive lobular cancer may include:

  • a swelling of all or part of your breast
  • changes in the shape of your breasts
  • pain in the breast or nipple
  • discharge from the nipple
  • thickening of the nipple or breast skin
  • a lump or swelling in the underarm area

Symptoms of metastatic cancer

Symptoms of metastatic cancer also depend on where the cancer has spread and its size. A metastatic tumor in the brain, for example, might cause headaches. A tumor in the lungs might cause shortness of breath.

Initial symptoms of metastatic cancer can include:

  • fatigue, loss of energy, and general weakness
  • unexplained weight loss
  • shortness of breath or trouble breathing
  • bone fractures or breaks
  • pain

Over the years, researchers have struggled to find out what causes cancers to spread or metastasize in the first place.

If researchers can identify the exact mechanisms behind this spread, then treatments can be developed to shut down those mechanisms, keeping cancer localized and easier to treat.

The “seeds and soil” theory, first presented by the English surgeon Stephen Paget in 1889, is still widely accepted and used in cancer research today. The theory suggests that the microenvironment of select organs plays a critical role in where cancer cells metastasize.

For example, when a plant goes to seed, its seeds are carried in all directions, but they only germinate (put down roots and grow) in soil that is compatible. Similarly, when tumor cells spread via blood or lymphatic fluid, they grow preferentially in organs or tissues that provide a suitable environment.

Researchers continue to study this and other hypotheses to better understand the mechanisms surrounding metastasis. For example, a 2015 study did not find why cancers metastasize in the first place, but it did uncover factors that aided the process of metastasis, these include:

  • attacks by the immune system
  • lack of oxygen and nutrients
  • large amounts of lactic acid from the breakdown of glucose (glycolysis) and increased cell death

What is the difference between invasive growth and metastasis?

Invasive growth refers to cancer that spreads:

  • within the breast
  • to nearby lymph nodes
  • to distant locations

Metastasis is when cancer spreads via the bloodstream or lymphatic system to distant locations in the body. Metastatic breast cancer is a specific stage of cancer that indicates the cancer has spread (“metastasized”) from the breast to a distant location.

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No single test can determine whether you have invasive cancer or metastatic cancer. Diagnosis usually requires a series of tests.

Imaging tests

Cancer may be seen on imaging tests like:

Blood tests and biopsies

Blood tests can provide some information but can’t say for certain if you have cancer or what type it may be.

If a tumor is found, a doctor will typically order a biopsy. Following a biopsy, a pathologist (a medical professional specifically trained to diagnose medical conditions using laboratory tests) will analyze the cells to determine their type. This analysis will help explain whether it’s primary or metastatic cancer.

In some cases, even though a metastatic tumor is discovered, the primary cancer can’t be found. That may be because the original tumor is too small to visualize on diagnostic studies.

Whether it’s early-stage invasive cancer or metastatic cancer, you’ll need to work closely with your doctor. Your oncology team will recommend potential treatments based on your test results.

Your doctor may also be able to give you information about clinical trials for people with metastatic cancer.

For invasive breast cancer, treatment options will depend on the type of cancer you have and the stage of cancer at the time of diagnosis. Ideally, the goal is to diagnose and treat invasive cancer before it has spread to distant sites.

Treatment options for invasive breast cancer

Some types of cancer tend to grow and spread faster than others. In these instances, more aggressive treatment may be necessary.

Common treatments for invasive breast cancer include surgery to remove the primary tumor and radiation therapy and/or chemotherapy to destroy any cells that may have been left behind.

For some types of cancer, doctors may also use:

Treatment options for metastatic breast cancer

Metastatic breast cancer is more difficult to treat because it has already spread to distant sites in your body. The same therapies can be used, but the goal is to control growth, ease your symptoms, and improve your quality of life.

You can learn more about treatment and prognosis for metastatic (stage 4) breast cancer here.

Your outlook for invasive breast cancer depends on how far the cancer has spread at the time of your diagnosis.

When caught early, the outlook for invasive ductal carcinoma is good, particularly if it’s localized to the breast.

According to the National Cancer Institute SEER statistics database, here are the 5-year relative survival rates for breast cancer based on women who received a diagnosis between 2013 and 2019:

Spread of cancer5-year relative survival rate
localized (cancer confined to breast)99%
regional (cancer has spread to nearby lymph nodes)86%
distant (cancer has spread to distant areas of the body31%

The 5-year relative survival rate for metastatic or stage 4 breast cancer is the same as distant in the above table, or 31%.

What is a relative survival rate?

A relative survival rate gives you an idea of how long someone with a specific condition may live after their diagnosis compared with someone without the condition.

For example, a 5-year relative survival rate of 31% means that someone with that condition is 31% as likely to live for 5 years as someone without the condition.

It’s important to remember that these figures are estimates.

Talk with your doctor about your specific situation. If you have cancer that’s in an advanced stage, your doctor may be able to recommend support groups or other resources that can provide assistance.

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