How do aromatase inhibitors work?


Question from Janis: Are aromatase inhibitors also anti-angiogenic drugs? Are they targeted therapies as well?
Answers - Andrew D. Seidman, M.D. I don't think of aromatase inhibitors as anti-angiogenic drugs. These are anti-estrogens that work by a different mechanism of action than tamoxifen. Aromatase is an enzyme that results in the production of estrogen outside of the ovaries in places such as the adrenal glands, which are sitting on top of the kidneys, as well as in fat, muscle, and in the liver. Aromatase is responsible for most estrogen production in the postmenopausal woman whose ovaries are no longer producing estrogen. The aromatase inhibitors (Arimidex, Femara, and Aromasin) all inhibit this enzyme and thus create a very low estrogen environment. This is thought to be the major mechanism by which aromatase inhibitors "target" estrogen receptor-positive breast cancer. It is important to also note that aromatase inhibitors should only be used in postmenopausal women or in premenopausal women whose ovarian function is suppressed by other means such as drugs or surgery.
Jennifer Armstrong, M.D. Dr. Seidman, would you not agree that the latter reference (i.e., the use of aromatase inhibitors in premenopausal women undergoing ovarian suppression) is not yet considered standard of care?
Andrew D. Seidman, M.D. Yes. The current optimal anti-estrogen treatment for premenopausal women with metastatic breast cancer is largely regarded as ovarian function suppression plus tamoxifen. The standard anti-estrogen therapy for premenopausal women with ER-positive early breast cancer is tamoxifen only. The role of ovarian function suppression as well as aromatase inhibitors is presently being studied in several large randomized Phase 3 trials.

On Wednesday, July 19, 2006, our Ask-the-Expert Online Conference was called Targeted Therapies: What is Right for You?Andrew Seidman, M.D. and moderator Jennifer Armstrong, M.D. answered your questions about different kinds of targeted therapies and how they work.

The materials presented in these conferences do not necessarily reflect the views of Breastcancer.org. A qualified healthcare professional should be consulted before using any therapeutic product or regimen discussed. All readers should verify all information and data before employing any therapies described here.

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