Treatment for Metastatic Breast Cancer

There is no single way to treat metastatic breast cancer (MBC). And though there are many options, even the leading experts may not approach metastatic breast cancer treatment the same way. So it's important to be comfortable speaking with your healthcare providers and asking them the questions you need answered.

Goals of Metastatic Breast Cancer Treatment

Treatments for MBC aim to shrink or stabilize the tumors. They also seek to prevent new tumors. This is done by killing cancer cells that are circulating in the body. Treatments are generally dictated by the location of the known metastasis (where the cancer has spread). And also by breast cancer types. What is appropriate treatment for someone else may not be the best for you. Your doctor may order regular scans or tests to see if your treatment is working. The disease may be stabilized for a long period of time by closely monitoring and changing treatments when necessary.

Types of MBC Treatment

Metastatic breast cancer treatments may be similar to those for an initial or local diagnosis of breast cancer. The most common breast cancer treatments include surgery, chemotherapy, radiation, hormonal therapy, targeted therapy, and immunotherapy. In general, metastatic disease will be treated with one therapy after another, pursuing each one as long as it remains effective. If one course of therapy stops working, your doctor will use another one. As a result, MBC treatments are often referred to as “first-line,” “second-line,” “third-line,” etc.

Metastatic Breast Cancer Treatment Factors

If possible, your metastases will be biopsied to determine their characteristics. These characteristics, in combination with the location of the metastases, will determine treatment. The location of your metastases may determine the treatment options available to you.

Bone Mets

These are the most common type of breast cancer metastases. They can cause pain, fractures and calcium in the blood. You may receive a bone targeted therapy to alleviate these issues and slow tumor growth. Radiation may also be used to lessen pain.

Liver Mets

The goal is to remove liver metastases if possible through surgery, radiofrequency ablation or cryosurgery. If inoperable, treatment will be given depending on the type of breast cancer.

Lung Mets

These may be removed by surgery. If surgery is not possible, treatment will be given depending on the type of breast cancer.

Brain Mets

The number and location of brain metastases guides treatment decisions. If there are relatively few tumors or a large tumor impacting surrounding tissue, surgery or stereotactic radiosurgery (such as Gamma Knife) may be used. Whole brain radiation may be recommended in patients with multiple brain metastases, especially if they are large. Some systemic therapies — including certain targeted therapies for HER2-positive disease — have also shown meaningful activity against brain metastases. Ask your oncology team whether systemic treatment options apply to your situation.

Your treatment options will also depend on the characteristics or type of MBC you have. For example:

ER/PR+ Disease

First-line therapy is endocrine (hormonal) therapy, which will be used as long as possible. Chemotherapy is typically used only when endocrine therapy fails. If the cancer has certain genetic mutations — such as PIK3CA, AKT1, or PTEN — additional targeted therapies may be options, including alpelisib (Piqray), capivasertib (Truqap), or a combination of inavolisib (Itovebi) with fulvestrant and a CDK4/6 inhibitor. Your doctor will test for these mutations to determine which options apply to you.

HER2+ Disease

All therapies will involve the use of anti-HER2 treatment. The treatment landscape for HER2-positive MBC has advanced significantly. Enhertu (fam-trastuzumab deruxtecan), often combined with Perjeta (pertuzumab), has demonstrated strong results as a first-line treatment and is considered a likely new standard of care. Other established options include Herceptin (trastuzumab), Perjeta (pertuzumab), Kadcyla (ado-trastuzumab emtansine), and Tukysa (tucatinib), which has also shown activity in brain metastases. Because this area is evolving rapidly, ask your oncologist about the most current options and available clinical trials.

Triple Negative

Treatment for metastatic triple-negative breast cancer (TNBC) has expanded considerably and depends on the specific characteristics of your cancer.

• Chemotherapy remains a core treatment, with multiple single-agent and combination regimens available.

• Immunotherapy: For people whose cancer tests positive for the PD-L1 protein (found in approximately 1 in 5 metastatic TNBCs), immunotherapy with pembrolizumab (Keytruda) combined with chemotherapy is an established first-line treatment option.

• PARP inhibitors: For people with an inherited BRCA1 or BRCA2 mutation, PARP inhibitors such as olaparib (Lynparza) and talazoparib (Talzenna) are FDA-approved treatments for HER2-negative metastatic breast cancer — not limited to clinical trials. Genetic testing is required to determine eligibility.

• Antibody-drug conjugates (ADCs): Sacituzumab govitecan (Trodelvy) is FDA-approved for previously treated metastatic TNBC. It targets the Trop-2 protein found in the majority of breast cancers.

• Platinum-based chemotherapy may also be considered for people with BRCA mutations.

Because TNBC tends to be more aggressive than other breast cancer types, participation in a clinical trial is often recommended. Ask your oncologist what trials may be available to you.

Palliative Care

Palliative care is given to improve a patient’s quality of life. Used for patients at any stage of their cancer journey, it can be particularly beneficial for women with MBC. The goal of palliative care is to manage distressing side effects of a disease or its treatment. Healthcare providers who specialize in this type of care have extensive training in the management of symptoms such as pain, neuropathy, nausea, diarrhea and constipation. They are also skilled at helping patients with psychological, social and spiritual problems related to a disease.