Femara (letrozole), an aromatase inhibitor, blocks the conversion of testosterone to estrogen.   Often, doctors use Femara in women who have had breast cancer that was positive for estrogen receptors. In our infertility practice, we use Femara as an ovulation induction agent that works similarly to Clomid.  Given for five days at the beginning of the cycle, Femara causes follicle growth. As well, Femara works in addressing PCOS and other forms of ovulation dysfunction.  It tends not to make the endometrium as thin or the cervical mucus as thick as Clomid does.  In patients with endometriosis that need ovulation induction, Femara keeps the estrogen levels low, which, in theory, should lessen the growth of endometriosis.

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Some studies have shown that the fibroids themselves produce estrogen.  Leiomyomata cells express both estrogen synthetase and aromatase, which will convert circulating androgens into estrogen.   With these facts, a new study was launched to compare the efficacy in shrinking fibroids with either Depo-lupron or Femara .Over the 12-week study period, researchers noted that the fibroids shrunk as much if not more in the letrozole group compared to the Lupron group. Side effects were also less severe in the Femara group.  Though long-term use of Femara for fibroid treatment has not been studied, breast cancer patients routinely take Femara for five years following surgery and chemotherapy.

A 2.5 mg per day dose of Femara can be used to treat endometriosis. This gives physicians another option for patients who do not want to use Lupron. The article about shrinking fibroids with Femara is enclosed for review. Feel free to contact Dr. Douglas with any questions.