News | June 13, 2007

Mayo Clinic Looks at the Numbers Behind Falling Breast Cancer Rates

June 14, 2007 - A new feature on now provides context and answers questions about the connection between HRT and breast cancer rates raised by a recent study in the New England Journal of Medicine, which reported a 9 percent drop in breast cancer rates from 2001 to 2004 among women age 50 and older.
Researchers point to a major drop in women's use of hormone replacement therapy (HRT) as the likely reason for the decline in breast cancer rates. The sharpest decline, 7 percent came in 2003, the year after a major national study of a combination hormone replacement therapy found the treatment increased the risk of breast cancer and heart disease. Many women were advised to stop taking HRT.
The new feature provides detailed answers to questions like: Are researchers certain that the reduction in HRT is the reason for the decline in breast cancer rates? It may be too soon to be certain, and there's probably more than one reason for the decline. Estrogen, the main hormone replaced in HRT, is a growth simulator. It could be that some breast cancers linked to HRT are still occurring but just not evident because they are growing more slowly. More long-term follow-up is needed.

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