How does advanced breast cancer develop?

Sometimes, cancer cells from the primary breast tumour can break away. They can then invade the breast tissue nearby but they can also travel through the blood or the lymphatic system, the body’s drainage system, to form new tumours in other parts of the body. These new cancers are described as secondary breast tumours or metastases. The secondary tumours are made up of the same breast cancer cells as the primary tumour.

The development of advanced breast cancer can happen at any stage, before or after treatment. It is more likely that breast cancer will spread to other parts of the body if it returns some time after successful treatment. In some cases, cells from the primary tumour may lay dormant for before becoming active and causing advanced breast cancer years later.

What are the symptoms of advanced breast cancer?

Symptoms of advanced breast cancer often don’t appear until the secondary tumours have grown big enough to cause problems. The symptoms experienced then vary according to the areas of the body that are affected and can include:

• Bone pain if cancer has spread to the bones.
• Breathing difficulties if cancer has spread to the lungs.
• Loss of appetite or weight, and possibly jaundice if cancer has spread to the liver.
• Neurological pain, weakness, blurred vision and headaches if cancer has spread to the brain.

Not all women with advanced breast cancer will experience these symptoms, and similar symptoms can also be due to other non-cancerous disorders. Advanced breast cancer is usually diagnosed after a series of extensive tests, never just on the basis of symptoms.

Diagnosing advanced breast cancer

Metastatic or advanced breast cancer is categorised as stage IV breast cancer. In around 10% of women, breast cancer is at stage IV by the time it is first diagnosed. This can be because it has been present but undetected in the breast for some time, or because the breast tumour is particularly fast-growing.

Advanced breast cancer can also be due to secondary tumours that develop from breast cancer that returns despite previously successful breast cancer treatment.

Tests used to detect advanced breast cancer

Your oncologist will usually only perform tests for advanced breast cancer if there is a reason to suspect that your cancer has spread to other parts of your body. These tests are not included as part of routine screening or follow-ups since many of them involve exposure to radiation.

The tests that your oncologist recommends will depend on your symptoms, if you have any, and where the doctor suspects the secondary cancers might be.