Secondary breast cancer is when breast cancer spreads from your breast to other areas of your body.

Secondary breast cancer is also known as metastatic, stage 4 or advanced breast cancer.

There isn’t currently a cure for secondary breast cancer, although there are treatments that can control it and relieve your symptoms. Many women diagnosed with secondary breast cancer are able to live active lives for several years.

It’s estimated there are around 35,000 people in the UK living with secondary breast cancer.

How does secondary breast cancer develop?

Secondary breast cancer develops when cancer cells break off from a tumour in your breast, travel to other areas of your body through your blood stream or lymph vessels (part of your immune system), and grow into a new tumour. This is called a secondary tumour or a metastasis.

The most common places for breast cancer to spread to are your bones, liver or lungs but it can also sometimes spread to other organs like your brain, skin or bowels. It’s possible for breast cancer to spread to more than one organ at once.

If you’re diagnosed with early breast cancer, you’ll be given tailored treatment to try and remove all the cancer cells from your body and stop secondary breast cancer from developing. But unfortunately, breast cancer cells can sometimes escape treatment.

Secondary breast cancer normally doesn’t develop until some time after your initial breast cancer treatment (often years) although a small number of women already have a secondary tumour when they are first diagnosed with breast cancer.

Why is secondary breast cancer currently incurable?

When breast cancer spreads to other organs it’s rarely possible to remove the tumours with surgery or radiotherapy. Treatment is more dependent on drugs like hormone therapy and chemotherapy that circulate your whole body.

But secondary breast cancer cells can change over time and often eventually develop resistance to these drug treatments. This means that while it’s often possible to control the growth of secondary tumours for some time, it’s difficult to permanently remove the cancer from your body.

If you want to know how long you’re likely to live with secondary breast cancer you can ask your treatment team, although it can be very hard for them to accurately predict how an individual cancer will progress. You don’t have to be given this information if you don’t want – just tell your treatment team if you’d rather not know.

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Breast Cancer Now’s health information is produced following best practice guidelines developed by the Patient Information Forum. 

Find out more about how we develop our health information and the Patient Information Forum.