New ASCO Guidelines Recommend Aromasin to Lower Risk in High-Risk Postmenopausal Women

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The American Society of Clinical Oncology (ASCO) has put out new guidelines on using hormonal therapy medicines to reduce breast cancer risk in postmenopausal women who have higher-than-average risk but haven’t been diagnosed. The new ASCO guidelines recommend that doctors talk to high-risk women about using the aromatase inhibitor Aromasin (chemical name: exemestane) to reduce risk. This is the first time ASCO has recommended Aromasin be used in this way.

The guidelines were published online on July 8, 2013 by the Journal of Clinical Oncology. Read “Use of Pharmacologic Interventions for Breast Cancer Risk Reduction: American Society of Clinical Oncology Clinical Practice Guideline.”(PDF)

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.

Aromasin works by stopping the body from producing estrogen, which limits the amount of estrogen available to stimulate hormone-receptor-positive breast cancer cells to grow.

ASCO guidelines published in 2009 recommended that doctors discuss only Evista (chemical name: raloxifene) with high-risk postmenopausal women to reduce risk and tamoxifen with both pre- and postmenopausal women to reduce risk. Both Evista and tamoxifen are approved by the U.S. Food and Drug Administration (FDA) to be used to prevent breast cancer in women who haven’t been diagnosed.

Both Evista and tamoxifen are SERMs (selective estrogen receptor modulators). SERMs block the action of estrogen in breast and certain other cells by sitting in the cells’ estrogen receptors. SERMs don’t affect all estrogen receptors the same way because they’re selective (as the name says). In bone cells, SERMs interact with the receptors the way estrogen does and strengthen bones. In breast cells, SERMs block the receptors’ interaction with estrogen and limit cell growth.

Aromasin isn’t approved by the FDA to be used for breast cancer prevention. ASCO experts decided to recommend that it be discussed as a preventive medicine based on research showing that high-risk postmenopausal women who took Aromasin were 65% less likely to be diagnosed with breast cancer than women who took a placebo (sugar pill).

Tamoxifen, Evista, and Aromasin are all pills taken by mouth.

The ASCO experts based the new guidelines on their review of research done between June 2007 and July 2012. Key recommendations in the guidelines are:

  • Tamoxifen (20 mg per day for 5 years) should be discussed as an option to reduce the risk of estrogen-receptor-positive breast cancer with both premenopausal and postmenopausal women age 35 or older who have a higher-than-average risk of breast cancer. Tamoxifen isn’t recommended for women who have a history of blood clots, stroke, or heart attack. Pregnant women, women who may become pregnant, and nursing mothers shouldn’t take tamoxifen. Women who are taking hormone replacement therapy (HRT) also shouldn’t take tamoxifen.
  • Evista (60 mg taken per day for 5 years) should be discussed as an option to reduce the risk of estrogen-receptor-positive breast cancer with postmenopausal women age 35 and older who have a higher-than-average risk of breast cancer. Evista shouldn’t be used to reduce risk in premenopausal women. Evista isn’t recommended for women who have a history of blood clots, stroke, or heart attack.
  • Aromasin (25 mg per day for 5 years) should be discussed as an alternative to tamoxifen or Evista to reduce the risk of estrogen-receptor-positive breast cancer with postmenopausal women age 35 and older who have a higher-than-average risk of breast cancer. Aromasin shouldn’t be used to reduce risk in premenopausal women.

Neither tamoxifen, Evista, nor Aromasin lowers the risk of hormone-receptor-negative breast cancer.

Tamoxifen, Evista, and Aromasin all may cause side effects, some of them severe. Hot flashes and night sweats are side effects of all three medicines, though they’re more common with tamoxifen and Evista. Joint pain is a more common side effect of Aromasin. Aromasin also may weaken bones and make women more likely to break a bone. All three medicines can sometimes cause dangerous blood clots in rare cases. This complication is more common with tamoxifen and Evista.

If you have a higher-than-average risk of breast cancer, it makes sense to do everything you can to keep your risk as low as it can be. There are lifestyle choices you can make, including:

  • maintaining a healthy weight
  • exercising regularly at the highest intensity possible
  • limiting or avoiding alcohol
  • limiting processed foods and foods high in sugar
  • eating healthy, nutrient-dense food
  • not smoking

You and your doctor also may be considering medicine to reduce your risk. Talk to your doctor about your preferences as well as the risks and benefits of each medicine. If you’re already taking tamoxifen or Evista and having unacceptable side effects, you may want to ask if Aromasin might be a better option for you. Together, you can make the best choice for your unique situation.

You can learn more about tamoxifen, Evista, and Aromasin in the Breastcancer.org Hormonal Therapy section.

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