Treatment for metastatic breast cancer has two goals. The first is to keep the cancer under control for as long as possible. The second is to maintain your quality of life, or overall enjoyment of life.

Treatments for HR-positive metastatic breast cancer may include:

• Targeted therapy (if you have HER2-positive disease)
• Hormonal therapy
• Chemotherapy
• Radiation therapy
• A combination of these treatments

Surgery is rarely done for metastatic breast cancer, but there are several reasons your doctor may recommend it. If other treatments keep the cancer from growing for some time, for example, your doctor might remove the primary, or original, tumor and in rare cases a metastatic legion from the lung or liver. Or, if you have pain or bleeding, your surgeon might remove the original tumor to help ease your symptoms.

In hormone-sensitive breast cancers, hormonal therapy can work as well as or even better than chemotherapy. There are several types of hormonal therapy for metastatic HR-positive disease, and you may be switched from one to another over time if one medicine stops working against the cancer:

• SERMs, or selective estrogen receptor modulators, work against estrogen receptor–positive metastatic breast cancers in pre- and postmenopausal women. The most commonly used SERM is tamoxifen. Toremifene (Fareston), which is closely related to tamoxifen, is used in postmenopausal women with hormone-sensitive metastatic breast cancer or with an unknown receptor status. Studies show it works as well as tamoxifen and has similar side effects.
   
• Aromatase inhibitors may be given as the first treatment for metastatic breast cancer in postmenopausal women, or after tamoxifen or other hormonal treatments stop working. The names of these medicines are:
  
  • Anastrozole (Arimidex)
  • Letrozole (Femara)
  • Exemestane (Aromasin)

Aromatase inhibitors increase the risk for bone thinning and osteoporosis, which can lead to bone breaks. Your doctor will monitor you and may recommend bone-strengthening medicine, if needed.

SERDs, or selective estrogen receptor downregulators, stop activity of estrogen on cancer cells, keeping them from growing. They are approved only for use in metastatic disease. They are used when the cancer no longer responds to other hormonal therapies. One common SERD is:

• Fulvestrant (Faslodex). Fulvestrant is injected into a muscle every 4 weeks. Hot flashes, mild nausea and fatigue are the major side effects.
• Megestrol acetate (Megace) is a human-made form of the hormone progesterone that counteracts some of the negative effects of estrogen. It is used when the cancer stops responding to other hormonal treatments. Megestrol, available as a pill or as liquid, is usually taken once a day, but it can also be taken in smaller doses at regular times during the day. One side effect is weight gain, so your doctor may prescribe megestrol if you have loss of appetite and weight loss. Megestrol also has a small risk of blood clots.

You may also consider taking part in a clinical trial, a study that looks at how well new medical approaches work in people. Clinical trials offer access to new treatments that are not otherwise available and may prove to work better than standard treatments. Taking part in a clinical trial also helps researchers develop better treatments for those diagnosed in the future.