About metastatic breast cancer

A diagnosis of metastatic breast cancer means breast cancer cells have spread outside the breast. They can travel anywhere in the body through the blood stream or lymphatic vessels.

Metastatic breast cancer can affect the bones, liver, lungs, lymph nodes or brain. Sometimes, but less often, metastatic cancer can appear in the skin, ovaries or abdomen. It has the potential to spread anywhere in the body.

Having metastatic breast cancer doesn’t mean that breast cancer will develop in all these areas. Where cancer spreads, and to how many places, varies between people and between types of breast cancer.

For a detailed guide to metastatic breast cancer, see Hope and hurdles. It can help you understand your diagnosis, treatments and support options for you and your family.

Terms for metastatic breast cancer 

Different words are used for metastatic breast cancer but they actually mean the same thing. Metastatic breast cancer is also called:

• stage IV (or stage 4) breast cancer
• secondary breast cancer (the original cancer in the breast is known as the ‘primary’ cancer or early breast cancer)
• advanced breast cancer.

Sometimes metastatic breast cancer is a person's first diagnosis of breast cancer. This is called ‘de novo’ metastatic breast cancer. De novo metastatic breast cancer is not common – about one in 20 people diagnosed with breast cancer will have metastatic breast cancer from the start.

When someone has 'metastases', it means the breast cancer cells have moved into another organ.

For example, when someone has ‘bone metastases’ from breast cancer, there are breast cancer cells in the bones. This is not the same as primary bone cancer. We treat this with breast cancer drugs.

It is important to know that ‘locally advanced breast cancer’ and ‘local or regional recurrence’ do not mean metastatic breast cancer, in most instances. They refer to breast cancer found in the area close to the original cancer. For example, in the tissue and lymph nodes around the chest, neck and breastbone.

Why some people develop metastatic breast cancer

It’s normal to ask how or why you have developed metastatic breast cancer, especially if you have had treatment previously for early breast cancer.

Unfortunately, we don’t yet know why some breast cancers spread and others don’t.

Most metastatic breast cancers are caused by breast cancer cells that have remained in the body after treatment.

They can stay inactive (‘dormant’) without being detected for months or years (sometimes more than 20 years) after a person completes treatment for early breast cancer.

For a reason researchers do not yet understand, sometimes the cancer cells begin to grow again.

Early breast cancer treatment reduces the chance that cancer will spread, but for some people it is not 100% effective.

De novo metastatic breast cancer happens most often when the cancer has been in the body for some time, undetected. During that time, the cancer cells have grown not only in the breast but in other parts of the body too.

How metastatic cancer spreads

When breast cancer cells spread, they move through your blood or lymphatic system to other organs or tissues in the body.

Metastatic breast cancer can be in more than one area of the body at the same time. But having metastatic breast cancer does not mean cancer will develop in all these areas.

Treatments for metastatic breast cancer 

Even though metastatic breast cancer has spread to another part of the body, it is treated as breast cancer.

For example, breast cancer that spreads to the bones is still breast cancer, not bone cancer. Doctors use breast cancer treatments rather than treatments for a cancer that began in the bones.

Find out about Treatments for metastatic breast cancer.

Who looks after your treatment and care

Many different people may be involved in your treatment and care, including:

• doctors, such as your medical oncologist
• nurses – breast care nurses, cancer nurses or cancer care coordinators
• allied health professionals, such as psychologists, physiotherapists and social workers.

Find out who makes up your treating team and what they do.