Since 2000 mammography rates have declined significantly in the United States, according to a new study. Published in the June 15, 2007 issue of CANCER, a peer-reviewed journal of the American Cancer Society, the study by Dr. Nancy Breen from the National Cancer Institute and co-authors confirms that screening mammography rates to detect breast cancer fell by as much as four percent nationwide between 2000 and 2005. This is the first study to show that the trend is nationwide among women for whom the test is intended to reduce mortality risk.
Regular mammography is the most efficacious screening test for the early detection of breast cancer available to women today. Not only does it detect early tumors in breast tissue, but also its widespread use by women over 40 years old since the 1980s has lead to a reduction in breast cancer mortality in the United States.
After years of increasing incidence, the rate of new breast cancer diagnoses has recently declined. How much of that drop is due to changes in mammography use has been the subject of debate. Prior reports show that between 1987 and 2000, screening rates among women over 40 years old increased from just 39 percent to 70 percent. However, evidence from some states and localities suggest that mammography rates have declined, putting at risk the decline in mortality rates previously observed. Dr. Breen and her co-investigators reviewed data from the National Health Interview Survey from 1987 to 2005 to estimate mammography screening rates.
Dr. Breen found that between 1987 and 2000, there was a steady increase in the use of mammography for women over 40 years old, while rates were relatively flat from 2000 to 2003. However, in 2005 screening fell by four percent compared to rates observed in 2000. This decline was significant for women over age 50. Some of the sharpest declines were seen among women who previously reported high screening rates: women between 50 and 64 years old; and women in higher socioeconomic levels.
This decline in screening is also noted to have coincided with a decline in reported incidence of breast cancer. Dr. Breen and her co-authors say they “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 researchers recommend “continued monitoring of trends in incidence, screening, and their underlying factors” and “consider what types of interventions would be needed should these downward trends continue.”