Postmenopausal women taking estrogen therapy may find reduced accuracy in their mammogram screenings for breast cancer. According to Dr. Mary Laya, a University of Washington assistant professor of medicine, estrogen replacement therapy often increases breast tissue density which increases the overall difficulty in reading mammograms. It may also lead a physician to mistakenly diagnose benign but dense breast tissue as cancer, or to miss a small tumor.
One quarter to one third off all postmenopausal women in the U.S. take estrogen replacement drugs to reduce symptoms of menopause or to prevent diseases such as osteoporosis and heart disease. Laya says women having estrogen replacement therapy should be told there may be more false alarms, and that women with a family history of breast cancer need to weigh the risks of the disease against the many benefits of estrogen therapy. In Laya’s study, the number of undetected cancers in women taking estrogen was very small.