Breast Tomosynthesis May Best Digital Mammography for Detection, Prognosis

By Marilynn Larkin, Reuters Health
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Three-D digital breast tomosynthesis (DBT) is associated with a better ability to correctly identify breast cancer in women ages 40-74 than 2D digital mammography (DM), researchers say.

"We found that the cancers detected by DBT tended to be smaller, node-negative and have biologies associated with a better prognosis compared to those found by 2D-alone screening," Dr. Emily Conant of the University of Pennsylvania in Philadelphia told Reuters Health.

​Doctor looks at breast imaging. Source: Getty

"We also found that the number of false-positive recalls decreased for all women screened with DBT compared with 2D mammography," she said by email. "Therefore, we believe that DBT screening has a very favorable risk-benefit ratio, especially in the very controversial group of younger women, aged 40-49 years."

Dr. Conant and colleagues analyzed data for 180,340 women (mean age, about 55) from three US research centers who were screened for breast cancer from January 2011 through September 2014 using DM (71.7%) and DBT (28.3%).

DBT screening was associated with better detection of smaller, more often node-negative, HER2-negative, invasive cancers (73.7% vs. 65.4%, respectively).

As Dr. Conant noted, compared with DM, DBT was also associated with lower recall for false positives (odds ratio, 0.64) and higher cancer detection (OR, 1.41) for all age groups, even after stratification by breast density.

Women ages 40 to 49 benefited most from DBT's cancer detection rate, particularly for smaller, node-negative invasive cancers. For those with nondense breasts, the cancer detection rate for DBT was 1.70 per 1,000 women higher than with DM; for women with dense breasts, the detection rate was 2.27 per 1,000 women higher for DBT.

Further, for these younger women, routine DBT screening was associated with seven of 28 breast cancers (25.0%) categorized as having a poor prognosis compared with 19 of 47 breast cancers (40.4%) detected with DM screening.

"We feel that DBT screening should be the standard of care for all women and that screening should begin at 40 years of age," Dr. Conant said.

"DBT equipment does cost more, but reimbursement is also higher by most insurances," she noted. "Therefore, the return on investment is rapid."

"Also, multiple studies have shown that screening outcomes are significantly improved with DBT (and) that when an abnormality is found on DBT, the workup or evaluation of the finding is more efficient - i.e., less additional imaging - compared to 2D alone screen-detected abnormalities," she concluded.

Dr. Manisha Bahl of Massachusetts General Hospital in Boston, coauthor of a related editorial, told Reuters Health, "Despite the burgeoning evidence that DBT is the 'better mammogram,' there are gaps in knowledge about this relatively new technology. How does DBT perform across different patient subgroups? What are the size and stage of cancers detected with DBT? Is DBT cost-effective? Are the benefits of DBT sustained over multiple rounds of screening? What are long-term patient outcomes?"

The current study addresses these knowledge gaps, "and thus represents an important contribution to the existing literature," particularly with regard to women ages 40-49, she said by email.

"Since its approval by the US Food and Drug Administration in 2011, DBT has been rapidly adopted in the US; however, not all practices offer DBT yet," she noted. "One of the reasons is increased cost, as the equipment is more expensive and the exams require more time to interpret than conventional 2D DM. Also, insurance coverage for DBT across the country is variable."


JAMA Oncol 2019.