Until the issue is resolved, Pierce added, women taking tamoxifen have alternatives to CYP2D6 inhibitors. Some SSRIs do not inhibit the enzyme. Using a different drug known as an aromatase inhibitor instead of tamoxifen to prevent breast cancer recurrence is another possible option.
"You should make the best judgment in terms of the appropriate medication for the patient, given her disease," said Pierce. "There are ways to work around the problem if tamoxifen is the best drug for a patient. But certainly aromatase inhibitors are very important drugs in our armamentarium for postmenopausal women with breast cancer."
One or more investigators in the U.S. study disclosed financial relationships with LabCorp, Medco Health Solutions, Roche Molecular Diagnostics, and Roche Molecular Solutions. Investigators in the study included Medco employees. Investigators in the Dutch study reported no disclosures.