FRIDAY, Dec. 15 (HealthDay News) -- Breast cancer incidence in the United States dramatically declined in 2003, possibly because many women stopped taking hormone replacement therapy after the 2002 Women's Health Initiative study found that it increased the risk of invasive breast cancer, according to research presented this week at the 29th annual San Antonio Breast Cancer Symposium.
Donald Berry, Ph.D., of the University of Texas M.D. Anderson Cancer Center at Houston, and colleagues analyzed 1990-2003 data from the National Cancer Institute's Surveillance Epidemiology and End Results database.
The researchers found that the U.S. breast cancer incidence rates, which increased at 1.7 percent per year between 1990-1998, began to decrease at 1 percent per year between 1998-2002 and plummeted 7 percent in 2003. The decrease was higher for estrogen receptor-positive than for estrogen receptor-negative breast cancers (8 percent versus 4 percent), and highest of all among women aged 50 to 69 (12 percent versus 4 percent).
After 2002, the number of women over age 50 who were taking hormone replacement therapy declined from an estimated 30 percent to about 15 percent. "It takes breast cancer a long time to develop, but here we are primarily talking about existing cancers that are fueled by hormones and that slow or stop their growing when a source of fuel is cut," Berry said in a statement.
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