Metastatic breast cancer originates in the breast but spreads to other parts of the body, such as the lungs, liver, or bones. Metastatic disease can’t be completely eliminated most of the time. But advances in treatment — especially with the use of hormone treatment and targeted therapies — are making it possible for many patients with metastatic breast cancer to live for many years with the disease.
Even after the original tumor is removed, microscopic tumor cells may remain in the body, which allows the cancer to come back and spread. Patients may initially be diagnosed with metastatic disease, or they may develop metastases months or years after their initial treatment. Metastatic breast cancer is becoming less common, due in part to screening and early detection as well as to effective treatment in the neoadjuvant and adjuvant settings (given before or after surgery), which prevents disease recurrence.
How have targeted therapies changed the treatment of metastatic breast cancer?
With all the effective, modern therapies that we have today, it’s possible for patients to live for a long time with metastatic cancer — many of them with no evidence of disease. For many patients, metastatic breast cancer becomes more like a chronic condition and can be kept under control, especially while patients are on active therapy and as long as their tumors don’t become resistant to the drugs.
One type of therapy that has made a big difference in keeping metastatic breast cancer at bay is a class of drugs that target HER2, a protein that is overexpressed, or amplified, in about 20% of breast cancers. Therapies that block this protein can substantially shrink tumors and have very few side effects.
Most breast cancers are driven by hormones, such as estrogen and progesterone. Hormone therapies — drugs that target the estrogen receptor or block estrogen production for patients with hormone receptor–positive breast cancer — are effective. There are many different hormone therapies available, so if a patient has been taking one for a long time and it stops working, we can try a second, or even a third, drug.
What about treatments for patients whose tumors are triple negative?
Triple-negative breast cancer means that tumor cells do not overexpress HER2 or express the estrogen or progesterone receptor. For these patients, we have many chemotherapy drugs that can control the cancer. When one stops working, we usually have many others that we can offer.
What about clinical trials?
It’s important that patients know they may be eligible for clinical trials of new, experimental agents when needed. A number of drugs are currently being investigated, including those that block the protein kinases CDK4/6, PIK3CA, and AKT, and drugs that block a mutated estrogen receptor. We are studying drugs that work against the androgen receptor in breast cancer; these are typically used in the treatment of prostate cancer. There are also new agents being tested for patients with HER2-positive cancer and immunotherapies that are being evaluated in patients with metastatic breast cancer.
Patients being treated for advanced disease at MSK also can undergo IMPACT testing, which looks for hundreds of cancer genes that may be mutated. Some of these mutations may play a role in cancer growth. We are actively studying drugs that target these mutations.
How are the goals of treating metastatic breast cancer different from treating patients with early-stage disease?
With early-stage disease, the intent of treatment is curative, and many patients are cured or go into remission.
With metastatic disease, the goals are to extend the lives of our patients and to improve their quality of life, as most patients will be dealing with a chronic condition. We do that by using advanced treatments that not only slow down or stop tumor growth but also reduce the symptoms related to metastatic breast cancer. These symptoms often arise when the cancer has spread to the organs, such as the lungs or liver, or to the bones.
What is the role of palliative care in treating metastatic breast cancer?
There’s a misconception that palliative care is given only at the end of life — that is not the case. To us, palliative care is the full spectrum of care that begins at the time of diagnosis, with the goal to improve the quality of life of our patients and their families, such as easing the symptoms of cancer.
Those symptoms may be physical, such as pain and fatigue, or they may be psychosocial or emotional.
How does MSK help patients cope with the stress and anxiety of being treated for advanced disease?
People living with metastatic breast cancer always have the disease in the background. But MSK offers a number of support services for patients and their families through our counseling and psychiatric services. We encourage patients to seek out support, and we encourage their friends and family to help support them.
Metastatic cancer is a disease that affects more than one person — not only patients but also their family and friends, as well as the clinical staff who take care of them. We see the pain that our patients and their families endure, and that’s hard to watch. We feel their pain too.