Breast Cancer Drug Not for Fertility

Femara May Cause Birth Defects; Risk Already Noted on Product

From the WebMD Archives

Nov. 30, 2005 -- The drug company Novartis is warning women not to take its drug Femara to boost fertility because of the potential risk of birth defects.

The drug company's Canadian branch is sending letters to Canadian fertility specialists about the risk, which isn't new and is noted on Femara's product information.

"A similar letter is expected to go out by the end of this week in the U.S.," says Kim Fox, director of global public relations for Novartis Oncology. Letters will be also sent in other countries, Fox tells WebMD.

Not Approved for Fertility Use

Femara isn't intended for use in fertility treatments. It's only approved for use by postmenopausal women with breast cancer.

Femara's labeling warns women not to take the drug if they are pregnant, might become pregnant, or are breastfeeding.

Femara is an aromatase inhibitor. It curbs production of estrogen, a female sex hormone which fuels some (but not all) breast cancers.

Fox says Novartis doesn't know how commonly Femara has been used for fertility. She says the company's worldwide safety database has records of 13 patients who have used the drug for that unapproved purpose -- known as "off-label" use.

The database just notes those patients' off-label use of Femara, not the outcome of any pregnancies they may have had.

Novartis' letter to Canadian fertility doctors appears on the web site of Health Canada, the Canadian health agency.

The letter came after Canadian researchers presented findings on Femara's off-label fertility use. The study by Marinko Biljan, MD, MRCOG, and colleagues was presented on Oct. 18 in Montreal at the annual meeting of the American Society of Reproductive Medicine.

Tracking Birth Defects

The study included 150 babies born to women who had taken Femara for fertility. The women had been treated at the Montreal Fertility Centre, where Biljan works. Some had only taken Femara; others had taken Femara along with other hormonal drugs.

Overall, there were no differences in birth defects between the two groups treated with the drugs, write the researchers. But compared with babies born to women who did not use the drugs, those born to Femara users had significantly higher rates of locomotor malformations and heart abnormalities and lower birth weights.


Maker's Letter

Fox tells WebMD that the Novartis letter to Canadian fertility specialists followed Biljan's presentation "to remind fertility specialists worldwide ... of the approved indications for Femara and to note the warnings regarding pregnancy, lactation, and premenopausal status contained in the Femara prescribing information."

The letter is posted on the web site of Health Canada, the Canadian health agency.

The letter states that Novartis "is aware that Femara is being used to stimulate ovulation in women who are infertile, or unable to become pregnant, as a treatment to increase their chances of becoming pregnant."

The letter continues with this list of facts:

  • Femara is authorized for use in postmenopausal women with breast cancer only.
  • The use of Femara for the purpose of inducing ovulation and increasing the chance of pregnancy is not an authorized use of this drug.
  • Femara is contraindicated and should not be used in women who may become pregnant, during pregnancy, and/or while breastfeeding, because there is a potential risk of harm to the mother and the fetus, including the risk of fetal malformations.
  • If there is exposure to Femara during pregnancy, the patient should contact her doctor immediately to discuss the potential of harm to the fetus and potential risk for loss of the pregnancy.

WebMD Health News Reviewed by Louise Chang, MD on November 30, 2005


SOURCES: Novartis Pharmaceuticals Canada, Nov. 24, 2005: "Subject: Femara (letrozole) should not be used in women who may become pregnant." Health Canada: "Public Communication: Health Canada Endorsed Important Safety Information on Femara (letrozole)." Kim Fox, director, global public relations, Novartis Oncology. Biljan, M. Fertility and Sterility, September 2005, Supplement 1, vol 84: pp S95. "Important Safety Information." Associated Press.
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