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Aromatase Inhibitors for Breast Cancer

Examples

Generic Name Brand Name
anastrozole Arimidex
exemestane Aromasin
letrozole Femara

Aromatase inhibitors are available as tablets. Follow your doctor's orders or the directions on the label.

How It Works

Aromatase inhibitors interfere with how much estrogen the body's tissues can make. This limits the amount of estrogen available in the body.

An aromatase inhibitor cannot lower estrogen levels made by the ovaries. That is why an aromatase inhibitor only works after menopause, when a woman's ovaries have stopped making estrogen and other hormones.

Why It Is Used

Aromatase inhibitors are used to treat early estrogen receptor-positive (ER+) breast cancer. They are also used to treat metastatic or recurrent ER+ breast cancer. An aromatase inhibitor can be used alone or after tamoxifen treatment.

Some doctors may use aromatase inhibitors "off-label" to treat infertility and endometriosis. This means that the U.S. Food and Drug Administration (FDA) has not approved this use.

How Well It Works

Aromatase inhibitors make it less likely that breast cancer will come back. These medicines work well for postmenopausal women who have had ER+ breast cancer. Studies that compare survival rates for aromatase inhibitors and tamoxifen show that women live about the same length of time when taking either of these medicines.1

Aromatase inhibitors may be given to postmenopausal women who have breast cancer, either at the beginning of treatment or after they are given tamoxifen.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

Call your doctor if you have:

  • Hives.

Common side effects of this medicine include:

  • Hot flashes.
  • Muscle or body aches.
  • Dizziness or mild nausea.
  • Diarrhea or constipation.
  • Weakness or fatigue.
  • Bone thinning. Aromatase inhibitors increase the rate of bone thinning that occurs normally in postmenopausal women.

Letrozole and anastrozole can increase your cholesterol.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

Do not use this medicine if you are pregnant or planning to get pregnant. If you need to use this medicine, talk to your doctor about how you can prevent pregnancy.

Checkups

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

References

Citations

  1. National Cancer Institute (2013). Breast Cancer Treatment (PDQ)—Health Professional Version. Available online: http://www.cancer.gov/cancertopics/pdq/treatment/breast/HealthProfessional.

Credits

By Healthwise Staff
Sarah Marshall, MD - Family Medicine
Douglas A. Stewart, MD - Medical Oncology
Last Revised August 14, 2013

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

© 1995-2014 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

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