How Is Metastatic Breast Cancer Treated?

Hormone therapy, chemotherapy, targeted therapy, and immunotherapy are the most effective treatments for metastatic (stage 4) breast cancer. These therapies use drugs to stop the growth of cancer cells.

Metastatic breast cancer occurs when cancer cells spread beyond the breast and to other organs like the bones, liver, brain, and lungs. It's incurable and the most advanced form of the disease. The goals of treatment are to prolong and improve the quality of life.

A team of healthcare providers can help treat metastatic breast cancer. These healthcare providers may include a medical, radiation, and surgical oncologist. An oncologist is someone who specializes in treating cancer.

Metastatic Breast Cancer Drugs

Many metastatic breast cancer treatment options are available. Some—hormone therapy, chemotherapy, targeted therapy, and immunotherapy—use systemic (whole-body) drugs to fight cancer cells throughout the body.

Your treatment options differ depending on a few factors:

• Where breast cancer has spread
• Whether cancer cells have certain hormone receptors or proteins
• Your menopausal status (whether your menstrual cycle has ceased or not)
• Your overall health and which treatments may bring you the least side effects

Hormone Therapy

These drugs treat hormone receptor-positive (HR+) breast cancers or sometimes unknown hormone receptor cancers. HR+ refers to a characteristic of the cancer cells. It means the hormones progesterone, estrogen, or both can attach to the cancer cells and stimulate their growth.

Hormone therapy drugs block cancer's access to estrogen in various ways. A healthcare provider may prescribe one of the following:

• Aromatase inhibitors: These drugs completely stop the production of estrogen in body tissues. You may take an aromatase inhibitor in the form of a pill once per day.
• Fareston (toremifene): This drug, which is available as a pill you take once per day, blocks estrogen from cancer cells. Farestron is approved for post-menopausal people.
• Faslodex (fulvestrant): Faslodex blocks estrogen receptors on cancer cells. This drug is generally reserved for post-menopausal people who've already tried other drugs like tamoxifen.
• Tamoxifen: This drug can block estrogen from stimulating cancer cell growth. It's available in the form of a pill that you typically take once daily.

Chemotherapy

Chemotherapy (chemo) uses strong chemicals to kill cancer cells or slow their growth. You can receive this therapy injected into the veins or by mouth.

Chemo drugs affect the whole body, so it can also kill healthy cells. You may experience side effects as a result, including:

• Diarrhea
• Fatigue
• Hair loss
• Loss of appetite 
• Menopause symptoms (e.g., hot flashes or vaginal dryness)
• Mouth sores
• Nail changes
• Nausea or vomiting
• Nerve damage 
• Weight changes

Chemo in the metastatic setting is often reserved for fast-moving cancers or cancers that have spread to the brain or liver. It's frequently paired with immunotherapy to treat metastatic triple-negative breast cancer.

Targeted Therapy

Targeted therapy attacks proteins on specific cancer cells. This drug-based therapy causes less damage to healthy cells than non-specific treatments like chemo. Targeted therapy is often combined with cancer treatments like chemo or hormone therapy. This improves the other treatments' effectiveness.

Targeted drugs can be administered as a pill, injection, or intravenous therapy (IV). Types of targeted therapy include:

• Antibody-drug conjugates: This type of targeted therapy helps bring chemodrugs straight to cancer cells. Examples include Enhertu (fam-trastuzumab deruxtecan), Kadcyla (ado-trastuzumab emtansine), and Trodelvy (sacituzumab goritecan).
• CDK4/5 inhibitors: These drugs block cyclin-dependent kinases (CDK) in HR+ breast cancers to stop their growth. Examples include Ibrance (palbociclib), Kisqali (ribociclib), and Verzenio (abemaciclib).
• Kinase inhibitors: HER2 is a kinase, or protein, that helps cancer cells grow. Kinase inhibitors can prevent this growth. Examples include Nerlynx (neratinib), Tukysa (tucatinib), and Tykerb (lapatinib).
• Monoclonal antibodies: These synthetic antibodies attach to the HER2 protein on cancer cells to stop their growth. Examples include Herceptin (trastuzumab), Margenza (margetuximab), or Perjeta (pertuzumab).
• mTOR inhibitor: This drug, available as Afinitor (everolimus), blocks a protein called mTOR. This protein helps cancer cells grow.
• PARP inhibitors: This class of drugs blocks PARP proteins, which repair damaged DNA in cells. Blocking these proteins can lead to cell death of cancer cells. Examples include Lynparza (olaparib) and Talzenna (talazoparib).
• PI3K inhibitor: Piqray (alpelisib) blocks the protein PI3K and prevents cancer cell growth.

Side effects may include heart damage, rashes, severe diarrhea, tiredness, and weakness. These side effects typically depend on the type of breast cancer type.

Immunotherapy

This drug-based treatment stimulates the immune system to fight breast cancer. It treats certain types of metastatic breast cancers in combination with chemo.

Immunotherapy can be effective because cancer cells can target immune cell proteins. This prevents the immune system from responding to the disease. Drugs can restore these proteins so the immune system can fight the cancer cells.

Side effects of immunotherapy may include:

• Allergic reactions
• Autoimmune issues, or when the immune system mistakenly attacks healthy cells and tissues
• Constipation
• Cough
• Diarrhea
• Fatigue
• Nausea
• Rash

Bone-Strengthening Drugs

Metastatic breast cancer that's spread to the bones can cause pain and increase fracture risk. A healthcare provider may prescribe drugs that can prevent these complications. Examples include Xgeva (denosumab) and Zometa (zoledronic acid). Both drugs block osteoclasts, or cells that break down damaged bone cells.

Side effects of bone-strengthening drugs can include:

• Bone damage in the jaw
• Flu-like symptoms (e.g., chills and muscle aches)
• Headaches
• Kidney problems 

Radiation Therapy

Radiation therapy is a localized treatment that uses high doses of radiation to kill cancer cells. Think of it like a strong X-ray.

Radiation is unlikely to destroy all cancer cells once they've spread. Healthcare providers prescribe this treatment less commonly for metastatic breast cancer. Radiation therapy is reserved for cases when a tumor is painful or for site-specific symptoms, such as bone fractures or liver blood vessel blockages.

This therapy can target specific areas of the body where cancer has metastasized (spread). Radiation can be external or internal (brachytherapy). External radiation uses beams that come from outside the body. This therapy can cause short-term symptoms, such as fatigue or skin issues, or long-term symptoms like organ damage.

Internal radiation uses a device with radioactive pellets placed in the affected tissue for a short time. This type can cause redness, bruising, pain, or infection.

Surgeries and Procedures

Surgery is less common to treat late-stage breast cancer. The goal of surgery is usually to remove most, if not all, cancer cells. Healthcare providers are unlikely to remove all cancer cells if the cancer has metastasized.

This treatment is more often reserved for painful cases of metastatic breast cancer, the same cases as radiation therapy. Radiation therapy may follow surgery.

Palliative Care

The goal of palliative care is to improve the quality of life and manage symptoms of people with chronic or severe illnesses. The oncology team often co-manages care with the palliative care team.

The palliative care team can consist of:

• Chaplains
• Nurses
• Nutritionists
• Social workers
• Specialist doctors

The care team can manage pain and help you make choices about your treatments and lifestyles. Palliative care is a more holistic type of medical care. Working with a palliative care team in addition to an oncology team can improve end-of-life care for people with metastatic breast cancer.

Complementary and Alternative Medicine 

A healthcare provider may recommend complementary and alternative methods alongside medical treatments. These methods can alleviate side effects, such as anxiety, fatigue, and stress, of metastatic breast cancer drugs, therapies, and surgeries.

Examples include:

• Acupuncture
• Massage
• Meditation
• Yoga

Clinical Trials

Research studies with human subjects look into potential treatment options for metastatic breast cancer. Participating in clinical trials helps researchers better understand how breast cancer works. Trials can provide you and others with new treatment options.

One treatment in trials, for example, is high-dose chemotherapy with a stem cell transplant. A stem cell transplant replaces the stem cells (blood-forming cells) damaged by chemo with healthy ones. The National Cancer Institute (NCI) keeps a database of clinical trials where you can search for their specific conditions.

Prognosis and Life Expectancy

The five-year relative survival rate for metastatic breast cancer is 31%. Research has shown that the life expectancy for people with metastatic breast cancer is about 2.5 months after diagnosis if it's untreated. Those who receive treatment have a life expectancy of about 36.4 months after diagnosis.

Keep in mind that this number depends on several factors, including age, overall health, and the type of breast cancer. The five-year relative survival rate for metastatic inflammatory breast cancer, for example, is 19%. Metastatic triple-negative breast cancer has a five-year relative survival rate of 12%.

Research has shown that the five-year survival rate for metastatic breast cancer has increased significantly since 1992. The advancement of different treatment options has allowed people with the disease to live longer with more manageable symptoms.

Living With and Managing Metastatic Breast Cancer

There's no cure for metastatic breast cancer. Treatments can alleviate symptoms and help prolong life expectancy. A healthcare provider can prescribe treatments that slow the progression of the disease.

Living with metastatic breast cancer can bring about anxiety, fear, and sadness. Here are some ways to help manage these emotions:

• Acknowledge negative feelings and then let them go. It's normal to feel scared about the future, but make sure this fear doesn't rule your life.
• Consider talking to family members, friends, or a mental health specialist about your feelings
• Make time for your hobbies and interests, such as going to the movies, reading, or traveling
• Try to focus on the present and find the small things that bring you joy each day