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Aromasin (chemical name: exemestane) is an aromatase inhibitor approved by the U.S. Food and Drug Administration (FDA) to treat:

  • postmenopausal women diagnosed with hormone-receptor-positive, early-stage breast cancer after they've taken tamoxifen for 2 to 3 years to reduce the risk of the cancer coming back
  • postmenopausal women diagnosed with advanced-stage or metastatic hormone-receptor-positive breast cancer 

Women stop taking tamoxifen when they start taking Aromasin.

Aromasin won't work on hormone-receptor-negative breast cancer.

Aromasin is a pill taken once a day. Most doctors recommend taking Aromasin at the same time each day.

Benefits of Aromasin

The large IES (Intergroup Exemestane Study) trial was started in 1998 and compared switching to Aromasin after taking tamoxifen for 2 to 3 years to staying on tamoxifen for 5 years. The results have shown that switching to Aromasin for 2 to 3 years AFTER taking tamoxifen 2 to 3 years (for a total of 5 years of hormonal therapy medicine) was better than staying on tamoxifen for 5 years for:

  • increasing the time before the cancer comes back in those who experience a recurrence
  • reducing the risk of a new cancer developing in the other breast

for postmenopausal women diagnosed with hormone-receptor-positive, early-stage breast cancer.

Research published in 2011 showed that Aromasin can lower risk in high-risk, postmenopausal women who've never been diagnosed with breast cancer. Aromasin is not approved by the FDA for this use, but doctors may consider it a good alternative to tamoxifen or Evista. In 2013, the American Society of Clinical Oncology (ASCO) released new guidelines on using hormonal therapy medicines to reduce breast cancer risk in high-risk women. These guidelines recommend that doctors talk to high-risk postmenopausal women about using Aromasin to reduce risk. ASCO is a national organization of oncologists and other cancer care providers. ASCO guidelines give doctors recommendations for treatments that are supported by much credible research and experience.

It's possible that the FDA may approve Aromasin to be used to reduce risk in high-risk, postmenopausal women who haven’t been diagnosed.

Side effects of Aromasin

Because Aromasin lowers the amount of estrogen in the body, less estrogen reaches bone cells, which can lead to bone thinning and weakening and a higher-than-average risk of broken bones. This side effect can be very troubling for some women. If you have osteoporosis, your doctor may recommend that you take tamoxifen rather than Aromasin because of this possible side effect.

Other common side effects of Aromasin are:

Joint pain from taking Aromasin can be troubling. But a 2008 British study suggests that women who experienced joint pain while taking hormonal therapy medicine were less likely to have the breast cancer come back (recur). Knowing that this side effect might indicate a reduced risk of the cancer coming back may help some women stick with treatment despite the side effects.

Some women may have other side effects while taking Aromasin:

Some side effects may mean that you're having an allergic reaction to Aromasin. If you have shortness of breath or chest pain, call your doctor immediately.

How long do I take Aromasin?

In most cases, you'll take Aromasin for 2 or 3 years. Doctors may recommend that some women take it for a longer time.

Does insurance cover Aromasin?

While costs vary, Aromasin can cost several hundred dollars per month. If you have health insurance, check with your insurance company to see if and how much of the cost of Aromasin is covered. If you don't have health insurance or your insurance doesn't cover the cost of Aromasin, ask your doctor or nurse about programs in your area that may be able to help.

Pfizer, the company that makes Aromasin, offers the First RESOURCE and the Pfizer Pfriends programs that may be able to help cover the cost of Aromasin. The phone numbers are:

  • First RESOURCE: 1-877-744-5675
  • Pfizer Pfriends: 1-866-706-2400

You can also visit the Aromasin website for more information.

You can also read the Paying for Your Care section for information on additional types of financial assistance and cost-lowering tips.

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