Anastrozole

Anastrozole (brand name Arimidex) is a type of hormonal therapy called an aromatase inhibitor. Doctors sometimes refer to hormonal therapy as endocrine therapy.

Anastrozole and other aromatase inhibitors lower estrogen levels in the body. They work by blocking the activity of aromatase, an enzyme that converts other hormones into estrogen. Lowering estrogen helps keep hormone receptor-positive breast cancer from getting the estrogen it needs to grow.

Other aromatase inhibitors include exemestane (Aromasin) and letrozole (Femara).

Who gets anastrozole?

Anastrozole is FDA-approved to treat hormone receptor-positive breast cancer in postmenopausal women. It can be used to:

• Lower the risk of recurrence (cancer coming back) after treatment for early-stage breast cancer
• Control the growth of advanced or metastatic breast cancer

Anastrozole can also be used to lower the risk of breast cancer in postmenopausal women who are at higher-than-average risk of developing it.

In some cases, anastrozole is used to treat hormone receptor-positive breast cancer in men and pre- and perimenopausal women. In these cases, anastrozole has to be combined with another medicine called a gonadotropin-releasing hormone agonist (GnRH agonist).

• In women, GnRH agonists temporarily keep the ovaries from producing estrogen. This is called ovarian suppression or ovarian shutdown.
• In men, GnRH agonists suppress testosterone production. Normally, some testosterone converts into estrogen in men. GnRH agonists interfere with this process so less estrogen is produced.

Some pre- and perimenopausal women choose to have their ovaries removed (oophorectomy) instead of taking ovarian suppression medicines. It’s important to know that oophorectomy causes early menopause that is permanent. You and your care team can talk about options and what is best for your situation.

How is anastrozole given?

Anastrozole is a 1 milligram tablet taken once a day.

Side effects and things to remember

Anastrozole can increase cholesterol levels. If you have a history of heart disease, tell your doctor before taking anastrozole. For women with a history of heart disease, anastrozole can increase the risk of heart problems. You and your doctor can discuss the risks and benefits of taking anastrozole in this situation.

Anastrozole can weaken the bones, which increases the risk of osteoporosis, a condition in which the bones become thin and brittle. This can lead to fractures. Talk to your doctor about your medical history. You may need to have your bone density and cholesterol levels checked before and during treatment with this medicine.

Anastrozole can also cause many of the same side effects as other aromatase inhibitors, including:

• Menopausal symptoms such as hot flashes, vaginal dryness and irritation (symptoms of genitourinary syndrome of menopause), and loss of interest in sex
• Stiffness and joint and bone pain
• High blood pressure
• Insomnia and fatigue
• Nausea and vomiting
• Weakness
• Headache
• Loss of appetite
• Weight gain
• Mood changes
• Constipation or diarrhea
• Dry skin
• Hair thinning