The breast cancer drug tamoxifen may have a new label warning. A panel of FDA advisors has recommended that the agency add a warning that postmenopausal women who use the drug to treat breast cancer face an increased risk of recurrence if they have the gene variation CYP2D6.

The panel left it to the FDA to determine whether the drug's label should recommend genetic testing of postmenopausal breast cancer patients before they are prescribed the medication. The language on the warning may be in the form of a suggestion. The label change could take 6 months to put in place, according to Lawrence Lesko, PhD, FDA pharmacology chief.