What is secondary breast cancer?

Secondary breast cancer happens when cancer cells spread from the cancer in the breast to other parts of the body. The cancer that starts in the breast is called the primary breast cancer. In many women, primary breast cancer never comes back after treatment. But sometimes breast cancer cells spread through the bloodstream or lymphatic system to other parts of the body.

The lymphatic system helps protect us from infection and disease. It’s made up of fine tubes that connect to groups of lymph nodes (sometimes called glands) throughout the body.

Breast cancer cells that have spread may eventually form another cancer or tumour. This is called a secondary breast cancer or a metastasis. Occasionally, women are diagnosed with secondary cancer at the same time as the primary breast cancer is found.

The secondary cancer is made up of breast cancer cells. Doctors treat it with the same drugs used to treat breast cancer. So a secondary breast cancer in the lung is treated as breast cancer, not as a lung cancer.

The most common places breast cancer can spread to are the:

This does not mean that secondary breast cancer will spread to all of these places.

Less commonly, breast cancer can spread to other parts of the body, such as the skin, bone marrow, ovaries or lining of the abdomen (peritoneum). If you need more information about this, you can call our cancer support specialists on 0808 808 00 00.

Local and regional recurrence

Breast cancer that comes back in the previously treated breast or in the operation scar is called a local recurrence.

If the cancer comes back in the lymph nodes in the armpit, close to the breast bone, or in the lower neck it’s called a regional recurrence.

When cancer cells block the lymph nodes in the armpit, fluid can build up in the arm causing swelling known as lymphoedema.

Even though these recurrences are not in the body’s organs, your doctor usually recommends tests to check the cancer has not spread further.

If the cancer has not spread anywhere else in the body, you will have surgery if possible, or radiotherapy to the area, or chemotherapy. Your treatment will depend on the previous treatments you had for primary breast cancer.

Back to Understanding secondary breast cancer

Why do cancers come back?

Sometimes, tiny cancer cells are left behind after cancer treatment. These can divide to form a new tumour.