Metastatic breast cancer is not a curable condition. However, treatment can prolong life, delay the progression of the cancer, relieve cancer-related symptoms, and improve quality of life. The median survival of individuals with metastatic breast cancer is 18 to 24 months, although the range in survival spans between a few months to many years. This article will review the treatment options for metastatic breast cancer. More detailed information about metastatic breast cancer is available by subscription.
GOALS OF TREATMENT
In addition to the goal of prolonging survival, treatment may help relieve cancer-associated symptoms, leading to an improvement or stability in quality of life.
APPROACH TO PATIENTS WITH A CHEST WALL OR BREAST RECURRENCE
Women treated for breast cancer are at risk of a local recurrence. For women who underwent breast conserving treatment (BCT), this may present as a new breast lesion. For women who underwent a mastectomy, it may present as a mass on the skin or chest wall. Regardless of primary surgery, all patients may also present with new disease in the axilla.
The approach to treatment will depend on the tumor size and location, as well as whether or not prior radiation was administered. Talk to your surgeon to determine the most appropriate treatment. If surgery is not an option, radiation therapy (RT) may be an alternative treatment.
APPROACH TO PATIENTS WITH METASTATIC DISEASE
All patients with metastatic breast cancer should receive systemic therapy. However, in certain circumstances, treatment may also involve surgery or radiation.
Symptomatic metastases — Treatment to a specific lesion may be required if symptoms are present or there is a threat of complications (ie, spinal cord compression or fracture, brain metastases at risk for herniation, or a pending fracture due to a lesion in the hip). This may require either a surgical approach or RT to stabilize the affected area. The approach must be tailored to the specific situation and the patient’s clinical status.
Systemic therapy — Systemic therapy includes the use of endocrine therapy, chemotherapy, and/or biologic agents. A choice between them depends on the tumor burden, patient symptoms, and several predictive factors including:
- Status of hormone receptors — Individuals with hormone-receptor (estrogen [ER] and/or progesterone [PR] receptor) positive cancers tend to do better than those whose tumors are ER- and/or PR-negative. Hormone-receptor positive patients are candidates for anti-estrogen therapy, but hormone-receptor negative patients are not. It is important that reassessment of both ER and PR be done during relapse because metastatic breast cancer does not necessarily have the same characteristics as the ones found in the primary breast cancer. (See 'Anti-estrogen treatment' below.)
- HER2 expression — With the availability of treatment targeted against the human epidermal growth factor 2 (HER2) receptor, a protein that is sometimes made by certain types of aggressive breast cancers, HER2 overexpression in breast cancer cells predicts who should receive HER2-targeted treatment. It is important to reassess the HER2 status of recurrent disease, as discrepancy between the primary and recurrent cancer occurs at least five percent of the time. (See 'HER2-targeted agents' below.).
Anti-estrogen treatment — Anti-estrogen treatment is also known as endocrine therapy. This includes:
- Selective estrogen receptor modulators (SERMs) — tamoxifen or toremifene
- Aromatase inhibitors (AIs) — anastrazole, letrozole, exemestane
- Selective estrogen receptor downregulators (SERDs) — fulvestrant
- Progestogens — Megestrol acetate or medroxyprogesterone
- Other sex steroid hormones — Progestins, estrogens, androgens
For premenopausal women, treatment aimed at preventing the ovaries from making estrogen, such as surgery to remove the ovaries (oophorectomy) or medications (ie, gonadotropin-releasing hormone antagonists, such as goserelin or leuprolide) are also effective.
Selective Estrogen Receptor Modulators (SERM) — These agents block estrogen from stimulating breast cells. The one used in the treatment of breast cancer is tamoxifen.
Tamoxifen is a pill that you take by mouth. It is commonly used as a first-line endocrine therapy for premenopausal women and for men with advanced breast cancer.
Most individuals with ER and/or PR-positive breast cancer will respond to tamoxifen therapy. However, some do not respond at all to tamoxifen. Others originally respond to tamoxifen but later become resistant. Unfortunately, most if not all breast cancers eventually stop responding to tamoxifen.
A subset of individuals with metastatic breast cancer experience a "flare" of their breast cancer within two days to three weeks after starting tamoxifen. This may cause an increase in bone pain, a high blood calcium level, and in individuals with breast cancer involving the skin, an increase in the size and/or number of these skin nodules, or skin redness. Tumor flares usually subside within four to six weeks. In the meantime, the symptoms can be treated with measures that reduce pain and lower blood levels of calcium. In severe cases, your doctor may tell you to temporarily stop taking tamoxifen until the flare subsides. Many doctors consider a flare reaction to be a sign that endocrine therapy is working. Side effects of tamoxifen include hot flashes, an increased risk of blood clots, uterine bleeding, and endometrial cancer.
Aromatase inhibitors — Aromatase inhibitors (AIs) are drugs that reduce estrogen levels in the body by blocking the protein that helps make estrogen outside of the ovary (aromatase). Drugs in this class include anastrozole, letrozole, and exemestane. They are indicated for use in postmenopausal women and can be used in men with metastatic breast cancer. However, AIs should not be given to women with intact ovarian function. Side effects of aromatase inhibitors include bone loss and bone fractures and pain in the muscles and joints.
Pure antiestrogens — Pure antiestrogens block the influence of estrogen on breast cancer cells. The agent from this class used in metastatic breast cancer is fulvestrant. It is given as a monthly intramuscular (IM) injection and is approved for use in postmenopausal women whose cancers have progressed on tamoxifen and/or an AI. Whether it is as useful for premenopausal women or for men with metastatic breast cancer is not known, but there is no reason to believe it would not have the same efficacy and toxicity in older women.
Side effects of fulvestrant include hot flashes, increases in your liver enzymes, injection site pain, and joint pain.
Sex steroid hormones — Progestins, estrogens, and androgens may play a role in the third- or fourth-line treatment of metastatic breast cancer.
- Progestins — These include both medroxyprogesterone or megestrol acetate and are taken as a pill. It is sometimes used in women who have stopped responding to tamoxifen. The side effects of treatment include blood clot formation, weight gain, fluid retention, and vaginal bleeding. In some studies, a reduction in the quality of life has been seen in women taken these drugs.
- Estrogen — For women who have progressed on multiple treatments with antiestrogens, the use of estradiol may be used. It is given as a pill and is taken daily. Side effects include vaginal bleeding, breast tenderness, nausea and vomiting, and venous thrombosis. Women on estrogen may also experience a tumor flare. For women who experience bleeding on estrogens, progestin treatment can provide control of symptoms.
- Androgens — The use of androgens in metastatic breast cancer is rarely used. Despite evidence that it can help tumors shrink, the side effects of treatment (virilization, edema, and jaundice) make it a less attractive option for both women and their clinicians.
Chemotherapy — Chemotherapy is a treatment given to slow or stop the growth of cancer cells. Chemotherapy is not given every day but instead is given in cycles. A cycle is the time it takes to give the treatment and then allow the body to recover from the side effects of the medicines. A typical cycle of chemotherapy is 21 or 28 days.
Chemotherapy drugs may be given alone, one after another, or in combination. There are a variety of drugs that can be used to treat breast cancer as both single agents or in combination. You should discuss which treatment is right for you with your doctor.
It is not clear how many doses of chemotherapy are best for individuals with metastatic breast cancer. Several studies have compared the benefit of continuous chemotherapy (giving chemotherapy until it becomes ineffective) versus intermittent chemotherapy (giving approximately six cycles of chemotherapy followed by no chemotherapy until the cancer progresses). In general, overall survival is the same in women treated with continuous or intermittent chemotherapy, although tumor growth may be slowed somewhat in women treated with continuous therapy. Intermittent chemotherapy may allow for a better quality of life. This is a reasonable option if your cancer-related symptoms stay under control during treatment.
Biologic therapy — Biologic therapy aims to target a specific protein or pathway in an effort to stop cancer cells from growing or dividing. For individuals with metastatic breast cancer, these agents include HER2-targeted agents and bone modifying agents.
HER2-targeted agents — Individuals whose breast cancers produce high levels of HER2 benefit from treatments that target this protein. There are two drugs in this category, trastuzumab and lapatinib. These are often used with chemotherapy or endocrine therapy in the treatment of metastatic breast cancer.
Trastuzumab — Trastuzumab is generally given IV once per week or once every three weeks. The most common side effect of trastuzumab is fever and/or chills. Heart failure develops in about 3 to 5 percent of women treated with trastuzumab. Trastuzumab-related heart damage may not be permanent, and improvements have been seen once trastuzumab is discontinued.
Lapatinib — Lapatinib is an oral medication that targets HER2 in a different way than trastuzumab. Lapatinib may be used alone, in combination with chemotherapy, or even in combination with trastuzumab. The most common side effects of lapatinib alone are diarrhea, a skin rash that resembles acne, and nausea.
Bevacizumab — The angiogenesis inhibitor, bevacizumab, is an active agent for the treatment of metastatic breast cancer, particularly when combined with the drug paclitaxel. It is often used as a first-line treatment of metastatic breast cancer. However, the benefit of bevacizumab is not clear and the Food and Drug Administration has recently rescinded its approval of this agent in metastatic breast cancer.
Bone modifying agents — While not used to treat breast cancer metastases, bone modifying agents are an important component of the treatment of bone metastases. These agents prevent the complications of breast cancer involving bones, such as fractures, spinal cord compression, and hypercalcemia of malignancy. Two classes of agents used are the bisphosphonates (pamidronate, zoledronic acid, clodronate and ibandronate) and the RANK (receptor activator of nuclear factor kappa B) ligand inhibitor, denosumab.
Role of surgery or radiation therapy — Some patients will develop metastatic disease that is confined to one organ, such as involvement in one area of the liver or one lobe of the lung. In these cases, treatment directed at the tumor site may be an option. This may consist of surgical resection, targeted radiation, radiation frequency ablation, chemoembolization, or other methods.
For those who are considered to be candidates for a local treatment approach, criteria are used to select patients most likely to benefit from site-specific treatment. Some criteria used to help identify patients most likely to benefit include:
- Good functional status— Patients who are minimally symptomatic from their cancer and independent with their activities of daily living tend to do better following surgery for metastatic disease.
- Limited number of sites of disease — Patients with limited disease appear to benefit from surgery compared to those with multiple sites of disease or with multi-organ involvement.
- Long disease-free interval — Patients who experienced a recurrence after a long period of remission do better than those with rapidly progressive cancer.
- Likelihood of a complete tumor resection — The outcomes following surgery are best in patients who undergo a complete resection of their disease with negative margins at pathologic review.
Treating metastatic breast cancer takes in to account the type of cancer that you have and whether your cancer expresses hormone receptors and/or HER2. It also takes in to account the extent of cancer you are living with.
Most clinicians recommend initial treatment with chemotherapy for rapidly progressive disease or in women with symptoms related to metastatic breast cancer. Combination chemotherapy is associated with increased responses compared to single-agent chemotherapy. However, treatment using single agents in a sequential fashion is associated with less toxicity than the use of a combination regimen. For all individuals with metastatic breast cancer the following recommendations apply:
- Individuals with hormone-receptor positive metastatic breast cancer who are not terribly symptomatic, do not have life-threatening disease, or evidence of visceral involvement do not require chemotherapy and can be treated with endocrine therapy.
- Some clinicians prefer to combine ovarian suppression (OS) or ablation (OA) with tamoxifen for peri- or premenopausal women with metastatic breast cancer. Although some clinicians also use an aromatase inhibitor in combination with OS or OA, the studies are too small to render a conclusion on the benefits of this approach.
- Sequential endocrine therapy is recommended to treat hormone positive breast cancer. Most clinicians will recommend chemotherapy only for individuals who progress despite two or three trials of endocrine therapy.
- For individuals who have not received prior treatment (ie, those who present with metastatic disease), those with ER-negative breast cancer, and those with tumors that do not respond to endocrine therapy, chemotherapy is indicated as primary treatment. There is no one standard of care.
- Available options include anthracyclines (eg, doxorubicin), taxanes (eg, paclitaxel or docetaxel), capecitabine, vinorelbine, gemcitabine, ixabepilone, and eribulin.
- Combination options include capecitabine and docetaxel, gemcitabine and paclitaxel. For chemotherapy naïve patients, doxorubicin (alone or as part of a combination regimen) is also used.
- Chemotherapy with biologic therapy, such as the angiogenesis inhibitor, bevacizumab.
- Individuals with HER2-positive breast cancers should receive HER2-directed therapy.
- For individuals with ER-positive cancer that is not life-threatening or symptomatic, endocrine therapy plus HER2-directed treatment (eg, lapatinib or trastuzumab) should be used. For similar patients with ER-negative cancer, single agent trastuzumab is an appropriate choice.
- For individuals with symptomatic, life-threatening disease, or disease that is involving the organs (eg, liver or lungs), combination chemotherapy with trastuzumab should be used. Most clinicians combine HER2-directed treatment with chemotherapy, such as paclitaxel, docetaxel, vinorelbine, carboplatin, and gemcitabine.
- Lapatinib can be used in combination with capecitabine, aromatase inhibitors, paclitaxel, or trastuzumab. It is indicated for individuals who have disease progression on trastuzumab.
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Breast cancer (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Breast cancer guide to diagnosis and treatment (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Treatment approach to metastatic hormone receptor-positive breast cancer: Endocrine therapy
Systemic treatment for metastatic breast cancer: General principles
Metastatic breast cancer: Local treatment
Systemic treatment for metastatic breast cancer: Single agent chemotherapy
Systemic treatment for metastatic breast cancer: Combination chemotherapy
Treatment of metastatic breast cancer in older women
Osteoclast inhibition in the management of bone metastases from breast cancer
Breast cancer in men
The following organizations also provide reliable health information.
Patient support — There are a number of online forums where patients can find information and support from other people with similar conditions.