When Breast Cancer Becomes Metastatic
Metastatic breast cancer is the most advanced stage of breast cancer, known as stage IV breast cancer. It occurs when the cancer develops the ability to spread to other organs in the body – most commonly the liver, lung, bone, soft tissues or brain. Even though the cancer involves other organs, it’s still treated as breast cancer. For example, a breast cancer involving the liver is not liver cancer, but metastatic breast cancer. We use breast cancer therapy to treat metastatic breast cancer regardless of the site of involvement.
Recent research estimates that more than 150,000 women in the United States are currently living with metastatic breast cancer. Most of the time, it develops months to years after a woman was initially treated for early-stage breast cancer. In the U.S., only about 6 percent of women already have metastatic disease when they are first diagnosed.
Metastatic breast cancer is incurable. However, recent advances in cancer therapy and supportive care have improved both the prognosis of this disease and women’s quality of life during treatment. The survival rate for metastatic breast cancer is highly individual and depends very much on how the cancer responds to treatment. While average survival with metastatic breast cancer is around two years, over a quarter of women with metastatic breast cancer are living with the disease over five years from diagnosis. (SEER data)
Treatment for metastatic breast cancer involves two goals: prolonging survival and treating any cancer-related symptoms to improve function and quality of life. The treatment is based on many different factors, including:
Tumor characteristics. Cancers with hormone receptors (ER/PR positive tumors) are often treated with anti-estrogen therapy (sometimes called hormone therapy). It is important to have a biopsy to assess for the presence of hormone receptors on the metastatic breast cancer cells, as metastatic breast cancer does not always have the same profile as the original tumor. HER2 expression is also important to determine, as the available treatments targeting the HER2 receptor have grown in number and efficacy.
Past breast cancer treatments. The previous treatments a woman has received for her breast cancer will determine, in part, which treatments are available or chosen for her metastatic disease.
Symptoms. Metastatic breast cancer can produce different symptoms, depending on the organ to which it has spread. Oncologists will choose therapy that addresses these symptoms in addition to using medications (such as pain medications). For example, Gamma Knife radiosurgery can be used to treat breast cancer lesions involving the brain, and various radiation therapy treatments can improve pain arising from bone metastasis and prevent complications.
In addition to anti-cancer treatments, women with metastatic breast cancer should take advantage of additional specialists who work to improve their quality of life during treatment. Our supportive care specialists, such as experts in pain and palliative care, psychologists and physical therapists can help to maintain and improve a patient’s function, well-being and independence during cancer therapy.
Participation in clinical trials offers patients with metastatic breast cancer access to new treatments and approaches that have the potential to improve outcomes. All patients with cancer should ask their oncology team about any appropriate clinical trials available to them at all stages of their disease.