Metastatic breast cancer is cancer that has spread beyond the primary site in the breast or local lymph nodes to more distant sites in the body. The most common places that breast cancer spreads to are the bones, liver, lungs and brain. Metastatic breast cancer is also known as stage IV, advanced or secondary breast cancer.

About 5% of the 20,000 people who are diagnosed with breast cancer each year in Australia are diagnosed with metastatic breast cancer. For these people, this is their first diagnosis of breast cancer. This type of metastatic breast cancer is called ‘de novo’ metastatic breast cancer – de novo means ‘from the beginning’.

However, most people diagnosed with metastatic breast cancer have previously been diagnosed with early breast cancer. Someone diagnosed with early breast cancer has a 20-30% chance that in their lifetime they will experience recurrence of their breast cancer somewhere else in their body. This could be years or decades after their original early breast cancer diagnosis.

Australia’s state and territory cancer registries do not systematically collect and report stage at diagnosis or recurrence data. Without this information, it is not possible to know exactly how many people are living with metastatic breast cancer in Australia. However, the Cancer Institute New South Wales recently calculated that there are about 24,000 people living with metastatic breast cancer in Australia, far more than many people had thought.

No, apart from in a very small number of people, metastatic breast cancer is not considered to be curable. However, there are many drugs available to treat metastatic breast cancer. Metastatic breast cancer is therefore considered to be a ‘treatable but not curable’ disease. This means that although we do not yet have a cure for metastatic breast cancer, people with metastatic breast cancer can be treated with a variety of different drugs, often for many years.