What is metastatic breast cancer?

Metastatic breast cancer (also called stage IV or advanced breast cancer) is not a specific type of breast cancer. It’s the most advanced stage of breast cancer.

Metastatic breast cancer is breast cancer that has spread beyond the breast and nearby lymph nodes to other organs in the body (most often the bones, lungs, liver or brain).

Although metastatic breast cancer has spread to another part of the body, it’s still breast cancer and treated as breast cancer.

For example, breast cancer that has spread to the bones is still breast cancer (not bone cancer). Therefore, it’s treated with breast cancer drugs, rather than treatments for a cancer that began in the bones.

How many people have metastatic breast cancer?

It’s estimated that more than 154,000 women in the U.S. have metastatic breast cancer. Men can also have metastatic breast cancer.

When can metastatic breast cancer occur?

Most often, metastatic breast cancer arises months or years after a person has completed treatment for early or locally advanced breast cancer. This is sometimes called a distant recurrence.

Some people have metastatic breast cancer when they are first diagnosed (called de novo metastatic breast cancer). However, this isn’t common in the U.S. (6 percent of diagnoses in women and 8 percent of diagnoses in men).