March 1, 2011
After a large drop in U.S. breast cancer rates among non-Hispanic white women between 2002 and 2003, those rates did not continue to decline between 2003 and 2007. Those are the findings of a new study from the American Cancer Society and the National Cancer Institute that appears online in the publication Cancer Epidemiology Biomarkers and Prevention.
In July 2002 results were published from the Women�s Health Initiative, a long-term national study, finding that postmenopausal women who used combined hormone therapy � estrogen plus progestin – had negative health effects including higher risk for breast cancer, heart disease, stroke, blood clots, and urinary incontinence.
The findings of the study results caused a �dramatic drop� in the use of postmenopausal hormone therapy and �breast cancer incidence rates among U.S. white women remarkably decreased by about 7% between 2002 and 2003,� according to the study. But no studies examined what happened to breast cancer rates in the United States after 2003.
Researchers studied data on female breast cancer incidence from the National Cancer Institute�s Surveillance, Epidemiology and End Results (SEER) 12 registries for the years 2000 to 2007. The data showed Breast cancer rates in non-Hispanic white women dropped between 2002 and 2003 but that drop didn�t continue between 2003 and 2007. There was no significant change in the rate among non-Hispanic white women. For non-Hispanic Black and Hispanic women, the data did not show the same drop from 2002-2003, and the study found no significant changes in breast cancer rates among those groups from 2003 to 2007.
The authors offer several possible reasons for the stabilization in breast cancer rates among non-Hispanic white women after 2003. Menopausal hormones are believed to encourage growth of hormone-sensitive tumors, and while the report shows that postmenopausal hormone therapy use has dropped, although the report indicates that postmenopausal hormone therapy use has continued to decline through 2008, the decrease in hormone therapy use after 2003 may not have been large enough to continue delaying diagnoses. A second factor, according to the study, may reflect the increased sensitivity of mammograms without the use of hormone therapy. Hormone therapy is known to increase breast density; the number of mammograms compromised by breast density would most likely decrease with the decrease in hormone therapy. The report also suggests that stable breast cancer rates may �in part reflect the relatively stable rates of screening mammography in the U.S. since 2000.�
