March 1, 2011 -- The decline in U.S. breast cancer rates seen in 2002 and 2003 in white women has not continued, according to a new report that tracks the numbers from 2003 through 2007.
''There was a dramatic decline between 2002 and 2003," says researcher Carol DeSantis, MPH, an epidemiologist with the American Cancer Society and a co-author of the report, conducted with researchers from the National Cancer Institute.
This decline, seen only in white women, was about 7%, she says, and widely attributed to women discontinuing menopausal hormone therapy after results of the large-scale Women's Health Initiative study, released in 2002, found an increased risk of heart disease, stroke, and breast cancer with the use of estrogen-progesterone therapy.
"It appears that the decline from [discontinuing] the use of hormone therapy has stabilized," DeSantis tells WebMD.
Two experts not involved in the study say the findings are not surprising, as they, too, speculate that the effect of discontinuing hormone use by now has stabilized.
The study is published online in Cancer Epidemiology, Biomarkers & Prevention.
DeSantis and colleagues obtained data from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) 12 registries for the years 2000 through 2007.
From 2003 through 2007, DeSantis and her colleagues found the overall breast cancer rates did not change significantly among white women in any age group.
There were no significant changes in breast cancer rates for African-American or Hispanic women from 2003 to 2007 either. Those two groups, however, did not experience the sharp drop found in white women from 2002 to 2003.
When the researchers looked at specific age groups and types of cancer, some rates increased and others decreased from 2003 to 2007. Among the findings:
Estrogen-receptor positive breast cancers, the most common type, increased 2.7% a year in white women 40-49.
Estrogen-receptor negative cancers, less common but aggressive, decreased in white women 40-49 and 60-69.
Among white women 60-69, breast cancer rates increased 4.8% from 2006 to 2007.
Among African-American women 40-49, rates of estrogen-receptor positive cancers increased 5.2% a year from 2003 to 2007.
African-American women also continued to have the highest rates of ER-negative cancers compared to white and Hispanic women.
The researchers say the stabilization in breast cancer rates may also be in part due to the relatively stable rates of screening mammograms in the U.S. since 2000.