Metastatic breast cancer (also called stage IV or advanced breast cancer) is not a specific type of breast cancer, but rather the most advanced stage of breast cancer.
Metastatic breast cancer is breast cancer that has spread beyond the breast 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 considered and treated as breast cancer.
For example, breast cancer that has spread to the bones is still breast cancer (not bone cancer) and is treated with breast cancer drugs, rather than treatments for a cancer that began in the bones.
It’s estimated that more than 154,000 women in the U.S. have metastatic breast cancer [1]. Some women have metastatic breast cancer when first diagnosed with breast cancer (about 6 percent of diagnoses in the U.S.) [2]. This is called de novo metastatic breast cancer.
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.
The risk of metastasis after breast cancer treatment varies from person to person. It depends greatly on:
The biology of the tumor (characteristics of the cancer cells)
The stage at the time of the original diagnosis
The treatments for the original cancer (trying to prevent recurrence)
