Breast cancer
drug linked to birth defects

The manufacturer of a breast cancer drug, letrozole, marketed under the brand name Femara, is warning fertility doctors that it has been associated with birth defects, a caution prompted by reports that the drug was being used to help a woman become pregnant.

Letrozole is approved for use only in postmenopausal women with breast cancer. But there is evidence some doctors have prescribed it as a fertility treatment because it suppresses estrogen and can promote ovulation.

Swiss drug manufacturer Novartis is sending letters to fertility doctors worldwide to reiterate a warning that the drug should not be given to women who may be pregnant, said spokeswoman Kim Fox.

The U.S. label on the drug already warns that it has been associated with birth defects, but concerns arose when a researcher in Canada published a report noting cases where the drug had been given to pregnant women. After the report, Novartis reviewed its safety database and found 13 reports of pregnant women receiving the drug worldwide, contrary to its warning label.

Of those 13, at least two had miscarriages and two had children with birth defects, Fox said. It was not clear how many of these women were given the drug to increase their fertility as opposed to some other reason.

Health Canada, the country's health care agency, issued the warning jointly with Novartis to fertility specialists, gynecologists, and obstetricians. In its letter in Canada, Novartis said Femara "should not be used in women who may become pregnant, during pregnancy and/or while breast-feeding, because there is a potential risk of harm to the mother and the fetus, including risk of fetal malformations." (AP)