Breast cancers detected with 3D mammography were smaller and more likely to not have spread to local lymph nodes than those detected by screening with standard digital mammography, a retrospective found.
Specifically, 73.7% of screening-detected breast cancers were 1 cm or smaller and node negative with 3D mammography examination compared with 65.4% with standard mammography, and this improved specificity was most evident in women ages 40 to 49, reported Emily F. Conant, MD, of the University of Pennsylvania in Philadelphia, and colleagues in JAMA Oncology.
Among this age group, 3D mammography — also known as digital breast tomosynthesis (DBT) — detected 4.41 invasive cancers per 1,000 examinations in women with non-dense breasts compared with 2.71 cancers per 1,000 examinations for standard mammography, a 1.70 per 1,000 improvement. Among women with dense breasts, the rate of improvement with tomosynthesis compared with standard mammography was 2.27 cases per 1,000 examinations.
In this age group, only 25.0% of cancers detected with tomosynthesis were classified as poor prognosis compared with 40.4% of those screened with standard mammography.
Of the more than 180,000 examinations included in the retrospective study, screening with 3D mammography was also associated with an almost 40% lower rate of recall (OR 0.64, 95% CI 0.57-0.72, P<0.001) and about a 40% increased rate of cancer detection (OR 1.41, 95% CI 1.05-1.89, P=0.02) compared with standard mammography.
“Our results supported the evolving literature showing that screening with DBT simultaneously improves breast cancer detection while reducing false-positive recalls,” wrote Conant and colleagues. Although these smaller cancers may not have transformed into more aggressive subtypes, they are “expected to be associated with better long-term prognosis.”
In an editorial accompanying the study, Manisha Bahl, MD, MPH, and Constance D. Lehman, MD, PhD, of Massachusetts General Hospital in Boston, highlight the importance of these results, particularly in women ages 40 to 49.
Currently, the Society of Breast Imaging and the American College of Radiology recommend beginning screening mammography at age 40, the American Cancer Society at age 45, and the U.S. Preventive Services Task Force at age 50.
“Conant and colleagues suggest that the combined gains of increased cancer detection and reduced recall rates for women aged 40 to 49 years who undergo screening using DBT may lead to a shift toward the balance of outcomes that are considered acceptable by the U.S. Preventive Services Task Force for women aged 50-59 years who undergo screening with [standard digital mammography],” Bahl and Lehman wrote. “This finding lends support to the suggestion that guidelines for routine breast cancer screening with DBT be reconsidered in women aged 40 to 49 years.”
The study included data from three research centers involved in the Population-based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium. Women were ages 40 to 74 and underwent screening with tomosynthesis (50,971 women) or standard mammography (129,369 women) from 2011 to 2014. 3D mammography was more common among younger women, those with dense breasts, and first-time screeners, but the data were adjusted to reflect these differences.
Lower recall rates occurred consistently among women who underwent tomosynthesis compared with standard mammography. This was true across all age groups and among women with non-dense (OR 0.62, 95% CI 0.54-0.72, P<0.001) and dense (OR 0.65, 95% CI 0.58-0.73, P<0.001) breasts. Tomosynthesis also detected a greater number of breast cancers compared with standard mammography, again, across all age groups.
Conant and colleagues reported receiving grants from the National Cancer Institute or the National Institutes of Health during the study. Conant also reported a grant from iCAD and consulting and speaker’s bureau fees outside the submitted work.
Lehman reported receiving research funding from and serving on the advisory board for GE Healthcare.