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How long do you need to take Aromasin?

Medically reviewed by Carmen Fookes, BPharm. Last updated on May 7, 2020.

Official Answer

  • Most women take Aromasin for two to three years.
  • Doctors may recommend some women take it for longer.
  • Aromasin is usually given after two to three years of treatment with tamoxifen, for a total of five years of continuous hormonal treatment.

Aromasin (exemestane) is a medication that is used to treat breast cancer in postmenopausal women. It is often given to women whose cancer has progressed despite surgery, radiation, or other cancer treatments.

The usual dosage is one 25mg tablet once daily after a meal. Most women take Aromasin for around two to three years. Doctors may recommend some women take it for longer.

Aromasin is usually given to women with estrogen-receptor positive early breast cancer who have already received two to three years of tamoxifen. The tamoxifen is stopped and the Aromasin is started to make up a total of five consecutive years of hormonal treatment.

  • Studies have shown that switching to Aromasin for two to three years AFTER taking tamoxifen is better than just staying on tamoxifen for five years.
  • Aromasin may also be given to women with advanced breast cancer whose disease has progressed following tamoxifen therapy.

How does Aromasin work?

The growth of many cancers of the breast is stimulated or maintained by estrogens. Aromasin works by irreversibly inactivating the enzyme aromatase and is structurally related to the naturally occurring androgen, androstenedione.

It acts so much like androstenedione, that the enzyme binds to it, and is unable to bind to anything else. This causes inactivation of the enzyme, an effect known as “suicide inhibition”.

Aromasin significantly lowers circulating estrogen levels but has no effects on the formation of corticosteroids, aldosterone, or any other enzyme.

Aromasin does not work on hormone-receptor negative breast cancer.

Aromasin is also not given to premenopausal women because it does not stop the ovaries from making estrogen. However, if women are willing to also take medication to suppress ovarian function, as well as effective nonhormonal birth control, then it may be given in certain circumstances.

What are the side effects of Aromasin?

Common side effects of Aromasin are:

  • Anxiety
  • Back pain
  • Bone and joint pain
  • Depression or low mood
  • Diarrhea
  • Dizziness
  • Dry skin
  • Hair changes
  • Headache
  • Heartburn or indigestion
  • High blood pressure
  • Hot flashes
  • Fatigue
  • Increased appetite
  • Increased sweating
  • Muscle and joint pain
  • Nausea
  • Sleeplessness
  • Swelling in the extremities (peripheral edema)
  • Visual disturbances.

Other side effects that may occur in less than 5% of women include:

  • Carpel tunnel syndrome
  • Diarrhea
  • Muscle cramps
  • Nerve pain
  • Osteoporosis or brittle bones.

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