Dense breast tissue can obscure abnormal growths, making it harder for physicians to analyze mammograms. According to two new studies, hormone-replacement therapy that includes estrogen can make breast tissue more dense, while the use of raloxifene, an estrogen-replacement drug, does not.
Researchers at the Group Health Cooperative of Puget Sound in Seattle analyzed pairs of density readings, taken 2 years apart, from 5,212 postmenopausal women.
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