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Decline of HRT Use Linked to Drop in Breast Cancer Cases

Posted: April 19, 2007

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After the WHI trial was halted, many women stopped taking hormones. In fact, the use of HRT had dropped by 38 percent in the United States by the end of 2002. In 2001, 61 million prescriptions were written for hormone replacement therapy. In 2002, there were about 47 million prescriptions. By 2003, that number had fallen to 27 million, and by 2004 just 21 million, the study authors noted.

The rate of breast cancer started dropping soon after the WHI results in 2002, according to the new study.

Between 2001 -- the last full year of combination HRT use -- and 2004, rates of breast cancer in the United States dropped by 8.6 percent in postmenopausal women. The rates of estrogen receptor-positive breast cancer -- those cancers known to be fueled by the hormone estrogen -- dropped by 14.7 percent in women between the ages of 50 and 69. Yet, rates of estrogen receptor-negative cancers dropped only 1.7 percent in the same time period, which further suggests that stopping HRT played a role in the decline.

"HRT is probably not something that causes cancer; it probably just fuels existing cancers," explained Berry. "If you feed it, it grows, and if you stop feeding it, it stops growing."

Berry said the Emory researchers looked at other potential causes for the decline in breast cancer rates, including whether fewer women were getting screening mammograms to detect tumors. The researchers also checked for environmental factors and the use of breast cancer drugs such as tamoxifen and raloxifene. But none of these factors had changed significantly enough to cause such a drop in breast cancer rates, the study authors said.