The addition of annual digital mammography for women 40 to 49 years old to the biennial screening of women 50 to 74 years old increases both the percentage of lives saved and life-years gained, according to a study published in the December edition of the American Journal of Roentgenology.
In 2009, the U.S. Preventive Services Task Force (USPSTF) recommended mammography screening guidelines calling for biennial mammograms for women between the ages of 50 and 74. Further, it recommended against routine screening for women between 40 and 49 years old.
The USPSTF acknowledged a 15 percent mortality benefit for screening women between the ages of 40 and 49, but cited the harms of unnecessary imaging tests, biopsies and radiation exposure. The USPSTF stated that it based this decision on the number needed to screen to save one life (NNS), but cited the number needed to invite (NNI) to the screening arm of a randomized controlled trial to save one life caused a lower benefit to harm ratio.
Lead author R. Edward Hendrick, PhD, with the Department of Radiology at the University of Colorado School of Medicine at the Anschutz Medical Campus, and colleagues “evaluated the implications of recent Cancer Intervention and Surveillance Modeling Network (CISNET) modeling of benefits and harms of screening to women 40-49 years old using annual digital mammography.”
For the study, the researchers used results of four CISNET models for lives saved and life-years gained form digital mammography screening in women between 40 and 49 years old to determine NNS, life-years gained and mortality reduction differences between biennial digital mammography in women ages 40 to 49 and film-screen mammography in women aged 50 to 74.
Results showed that adding annual digital mammography of women between 40 and 49 years of age to the biennial screening of women 50 to 74 years old increased the number of lives saved by 27 percent. Additionally, it raised life-years gained by 47 percent.
Hendrick and colleagues concluded that annual digital mammography screening in women between the ages of 40 and 49 saved 42 percent more lives and life-years than biennial exams.
They found the number needed to save one life with annual digital mammography in women 40 to 49 years old was 588.
“It should also indicate the importance of looking beyond [randomized controlled trial] data to assess modern screening practices,” the authors wrote. “RCTs that use breast cancer mortality as an endpoint require several decades of follow-up to appropriately assess mortality differences between invited and uninvited groups, especially in younger women. That long assessment period ensures that RCTs with mortality endpoints are incapable of estimating the substantially greater benefits of current screening technology and medical practice, both of which have improved dramatically since the last RCT of screening mammography.”