Metastatic breast cancer

Only about 5% of Finnish breast cancer patients receive an initial diagnosis of metastatic breast cancer. However, some patients who have early-stage breast cancer may later develop recurrent breast cancer in the metastatic form.

Metastasis means that cancerous lesions (metastases) have spread to other parts of the body such as the bones, liver and lungs. Metastatic breast cancer is currently thought to be an incurable disease, but treatments can be quite effective for many years. The goal of treatment is to destroy metastases or make them shrink. This stops or slows cancer progression, relieving any symptoms the disease may be causing.

Treatment of metastatic cancer is customized individually. Factors considered include the cancer subtype, extent of spread, symptoms (if any), prior treatments and treatment outcomes, and the patient’s other diseases and overall health.

Metastatic cancer treatment involves drug therapy, radiotherapy, and sometimes surgery as well.

The cancer subtype determines the drug therapy used. Options include several kinds of chemotherapy, as well as hormonal therapy if hormone receptors are expressed in the tumor. Treatment can often be started with hormone therapy in receptor-positive disease, later transitioning to chemotherapy if the cancer progresses. Alternatively, 3 to 6 months of chemotherapy may be given first, followed by hormone therapy.

The HER2-positive disease subtype may also be treated with drugs that target the HER2 surface receptor. Such drugs are most effective when combined with chemotherapy, so this subtype is often initially treated with a combination of chemotherapy and an anti-HER2 drug. If the response to this treatment is strong, chemotherapy may be stopped and the anti-HER2 drug continued alone or in combination with hormone therapy. The side effects of this treatment are considerably milder compared to chemotherapy.

Radiotherapy and surgery may also be used to treat metastatic breast cancer. One reason for using radiotherapy is to reduce the risk of fractures caused by bone metastases. Surgery is used less often, but may be appropriate for treating isolated brain metastases, for example.