Metastatic breast cancer

Metastatic breast cancer is cancer that has spread from the first (primary) tumour in your breast to another part of your body. It is also known as secondary breast cancer, advanced breast cancer or stage 4 breast cancer.

Your cancer may be advanced when it is first diagnosed, or your cancer may have come back or spread sometime after your first diagnosis (recurrent cancer).

Metastatic breast cancer treatments are to keep the cancer under control, rather than to cure it. There are many treatments that can keep the cancer under control, sometimes for many years.

Most people diagnosed with metastatic breast cancer were diagnosed with primary breast cancer previously. They have been through tests, treatments and side effects. They are familiar with their healthcare team in the hospital and have learned how to cope with the disease.

Sometimes a patient's first diagnosis is metastatic breast cancer: their cancer has already spread by the time it is diagnosed – they have not had a previous diagnosis of breast cancer. This is known as de novo metastatic breast cancer. ‘De novo’ means the breast cancer is metastatic ‘from the start’.  

Being diagnosed with metastatic breast cancer as your first cancer diagnosis is not common, but it can be overwhelming.

Your healthcare team will guide you through your diagnosis and treatment, and we are here to help too. Our Support Line nurses can help and support you, and give you information on counselling and other services. 

Often primary breast cancer is cured, but sometimes treatment does not remove all the breast cancer cells. These breast cancer cells may be so small that they can’t be picked up on scans. 

Cancer cells may spread through the bloodstream or lymphatic system to other parts of the body, where they may eventually form another cancer (tumour). Cells may also spread to another part of the body before treatment starts. 

The cells may be inactive for many years and then start to grow and divide to form a new tumour. Doctors and scientists do not know why this happens.

The most common places for breast cancer to spread to are the bones, liver, lungs, brain, skin or lymph nodes. Less commonly it can spread to other parts of the body, such as the bone marrow, ovaries or lining of the abdomen (peritoneum).

The metastatic cancer is made up of breast cancer cells. The metastatic cancer is still breast cancer, even if it is in another part of your body. For example, if breast cancer spreads to your lung, it is described as metastatic breast cancer in the lung, not lung cancer.

Finding out your cancer has spread can be very difficult to deal with emotionally, but in time most people find a way to cope and feel better. We have information about coping with a diagnosis of metastatic cancer.

Medical content updated from our 'Metastatic (secondary) breast cancer' booklet (2023), reviewed by Dr Megan Greally, Consultant Medical Oncologist, Alexandra Stanley, Medical Oncology Clinical Nurse Specialist and Mary O'Kelly, Daffodil Centre Nurse.