Based on government health surveys, the percentage of women 40 and older who reported getting a mammogram in the last one to two years dropped from 76.4 percent in 2000 to 74.6 percent in 2005, the CDC says.
If the trend continues, it could mean a rise in breast cancer deaths in the future, the agency warns.
Women should get mammograms to screen for breast cancer every one to two years, starting at age 40, advises the CDC.
Mammograms are X-rays of the breast. While they don't single-handedly diagnose breast cancer and aren't guaranteed to spot all breast tumors, mammograms can be lifesavers.
Screening mammograms — the kind given routinely even when the woman doesn't have a breast lump — have been shown to cut breast cancer deaths by 20 percent for women in their 40s and by 20 percent to 35 percent for those 50 to 69, according to the CDC.
Reasons for the screening downturn aren't clear but may be due at least in part to a shortage of facilities and trained breast specialists for the growing number of women 40 and older.
Study Based on Health Surveys
In its study, the CDC analyzed data from annual government health surveys conducted by telephone from 2000 to 2005.
Surveyors asked women 40 and older if they had ever gotten a mammogram, and, if so, how long it had been since their last one.
The number of women 40 and older participating in the surveys ranged from nearly 14,400 in 2001 to more than 95,000 in 2004.
Mammograms Save Lives
The CDC calls the drop in mammogram screening "slight."
But "because mammography screening every 1-2 years can significantly reduce mortality from breast cancer, continued declines in mammography use might result in increased breast cancer mortality rates," states the CDC in its Morbidity and Mortality Weekly Report.
The American Medical Association, American College of Obstetricians and Gynecologists, and American Cancer Society also recommend screening mammograms for women starting at age 40, though those groups may recommend different timetables for such mammograms.
For instance, the American Cancer Society recommends women 40 and older get a screening mammogram every year.
Women at high risk for breast cancer may need to start screening earlier.
SOURCES: CDC, Morbidity and Mortality Weekly Report, Jan. 26, 2007; vol 56: pp 49-51. News release, CDC. American Cancer Society: "Mammograms and Other Breast Imaging Procedures."
By Miranda Hitti
Reviewed by Louise Chang, M.D