The drop in mammography rates in the United States in recent years is cause for concern because it could contribute to a future rise in breast cancer deaths, according to an analysis of data from representative national surveys published early online in Cancer.

Scientists from NCI's Division of Cancer Control and Population Sciences (DCCPS), led by Dr. Nancy Breen, examined data from the Centers for Disease Control and Prevention's National Health Interview Surveys (NHIS) and found a decline in mammography screening in 2005 compared with 2000 - from 70 percent to 66 percent. After many years of increases in mammography use, "this report establishes for the nation what has already been observed in some local data. It confirms that use of mammography may be falling. Although small, this decline is cause for concern, as it signals a change in direction."

Mammography screening rates were lower in 2005 than in 2000 for nearly all the groups of women examined. "The largest significant declines were among women who have traditionally used mammography at high rates, including the 50-64 age group, those with higher incomes, and women aged 40-64 with private, non-HMO insurance coverage," the DCCPS investigators noted.

When screening rates drop, women with breast cancer will be diagnosed later, resulting in a short-term drop in incidence, they add. "Consequently, we are concerned that some of the observed decline in incidence may be due in part to the leveling off and reduction in mammography rates." The trend "may presage a future increase in mortality from breast cancer" from later detection of more advanced disease. "If future NHIS data continue to show a decline in mammography use, then we as a nation need to be prepared to address it," the NCI scientists concluded.

The recent decline in breast cancer incidence rates was examined in a separate study published May 3 in Breast Cancer Research. Scientists from the American Cancer Society, led by Dr. Ahmedin Jemal, examined data from NCI's Surveillance, Epidemiology, and End Results (SEER) program.

"Two distinct patterns are observed in breast cancer trends," they reported. The downturn in incidence rates in all age groups above 45 years coincides with a plateau in mammography use, which typically reduces incidence rates "due to a reduced pool of undiagnosed cases." The sharp decrease in incidence from 2002 to 2003 that occurred in women 50 to 69 years old who predominantly, but not exclusively, had ER-positive tumors may reflect the early benefit of the reduced use of hormone replacement therapy. A number of investigators within NCI-funded initiatives are now examining the contribution of recent changes in screening and hormone therapy to breast cancer trends.