Metastatic breast cancer starts in the breast but then spreads to other parts of the body. For example, it could spread to the bones or the lungs. It's also referred to as stage 4 or advanced breast cancer. It is the most severe form of the disease. 

Although rates of recovery from metastatic breast cancer are lower than for other forms of cancer, the number of U.S. women living with the disease is growing. New treatments can lessen symptoms and keep the cancer from spreading further, helping women live longer.

A recent study from the National Cancer Institute found:

• In 2020, an estimated 168,000 women in the U.S. are living with metastatic breast cancer.
• The five-year survival rate of women diagnosed with metastatic breast cancer is increasing, especially among women aged 15 to 39.
• About one-third of women diagnosed with metastatic breast cancer have lived with it for five or more years.
• Some women may live 10 or more years after being diagnosed.

More research is needed to address the health care needs of women who live with this condition, according to the study.