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Aromatase inhibitors to block estrogen production
Source: Hormone Therapy for Breast Cancer, National Cancer Institute.
Source updated: December 2, 2025 · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary. Independent clinical review is pending.
NCI patient treatment article for this disease Exact source article; not a clinically reviewed indication or current-standard recommendation.
Context: Hormone Therapy for Breast Cancer / What types of hormone therapy are used for breast cancer?
Aromatase inhibitors are used to block the activity of an enzyme called aromatase, which the body uses to make estrogen in the ovaries and in other tissues. Aromatase inhibitors are used primarily in postmenopausal women because the ovaries in premenopausal women produce too much aromatase for the inhibitors to block effectively. However, premenopausal women can take aromatase inhibitors if they are given together with a drug that suppresses ovarian function.
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Men with advanced breast cancer who are treated with an aromatase inhibitor will also be given a GnRH agonist, such as goserelin or leuprolide.
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Aromatase inhibitors used to treat breast cancer include:
anastrozole
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letrozole
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exemestane
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Preserved source evidence · Independent clinical review pending · Not medical advice