After a decade of dramatic increase in the use of mammograms, the proportion of American women who reported a recent test stabilized in 2000 through 2003, according to Nancy Breen, Ph.D., of the National Cancer Institute here.
But the proportion of women reporting a recent mammogram -- defined as within the previous two years -- had fallen by 2005 to below 2000 levels, Dr. Breen and colleagues reported online in the journal Cancer. So they concluded that the decline in breast incidence may be partly due to a drop in mammography detection.
The mammography decline -- from 70.1% in 2000 to 66.4% in 2005 -- was statistically significant on the basis of a t test, the researchers reported, although no P-value was given.
The sharpest decline was among women ages 50 through 64: In 2000, 78.6% reported a recent mammogram, compared with 71.8% in 2005, a significant drop of 6.8%, the researchers said.
Last December, Peter Revlin, M.D., Ph.D., reporting at the San Antonio Breast Cancer Symposium, revealed that a leveling-off and possible decline in the incidence of breast cancer, starting in 2003, coincided with a falloff in the use of hormone-replacement therapy.
Dr. Breen and colleagues noted that the mammography decline occurred during approximately the same period as the decline in breast cancer incidence.
"Consequently, we are concerned that some of the observed decline in incidence may be caused in part by the leveling off and reduction in mammography rates," they said.
The issue of mammography use is also important, they noted, because it is now accepted that screening reduces breast cancer mortality.
The finding comes from an analysis of data from the National Health Interview Survey, an annual in-person survey of more than 38,000 individuals that is designed to produce national estimates.
Mammography rates were lower in 2005 than in 2000 for nearly all of the different groups of women examined, the researchers said, and the largest drops were among women who traditionally have used mammography at high rates.
- The mammography rate among women whose family income was greater than five times the national poverty level fell from 82.8% in 2000 to 76.5% in 2005.
- Among non-Hispanic white women, the mammography rate fell from 72% to 68%.
- Among college graduates, the rate fell from 80% to 76.3%.
- Among women who reported a usual source of care, the rate fell from 73% to 68.9%.
The study is in agreement with several more restricted analyses, including declines seen in some health management organizations, in Medicare claims in 33 states, and in recent data from the Behavioral Risk Factor Surveillance System, Dr. Breen and colleagues said.
The report "establishes for the nation what already has been observed in some local data," the researchers said. "This change needs to be monitored carefully and also may call for intervention."
|The study was conducted by employees of U.S. government agencies. The authors did not report any potential conflicts of interest.|
- Reviewed by Zalman S. Agus, MD Emeritus Professor at the University of Pennsylvania School of Medicine
CancerSource Reference: Breen N et al. "Reported Drop in Mammography: Is This Cause for Concern?" Cancer 2007; DOI 10.1002/cncr.22723.