A 10-year study from researchers at the Yale School of Medicine has demonstrated that use of digital breast tomosynthesis (DBT) increases breast cancer detection rates and significantly reduces the rate of advanced cancer than does the standard screening method of two-dimensional digital mammography.
Mammography has long been considered the gold standard breast cancer screening method, but research has shown that conventional 2D mammography, which uses a low-dose X-ray to capture images inside the breast from two angles, fails to detect as much as 20 percent of cancers. In addition, mammography can also produce false positives, which result in additional and unnecessary testing.
DBT, however, is an advanced form of mammography that can create a three-dimensional image of the breast by reconstructing images taken from three different angles. Previous studies have also found DBT to have higher detection rates of breast cancer than digital mammography.
“This study is the first to compare 10 years of data on breast cancers detected by DBT to digital mammography-detected cancers,” said co-author Jaskirandeep Kaur Grewal, a previous student in the Yale School of Medicine physician associate program. The research appears today in the journal Radiology.
For this long-term study, the Yale team collected a cohort of nearly 273,000 mammogram screenings. Of these, 35,544 were performed with digital mammography and 237,394 were from DBT screening. From this cohort, a total of 1,407 cancers were detected—142 by mammography and 1,265 by DBT.
Co-first author Liane Elizabeth Philpotts, MD, a professor of radiology at Yale School of Medicine noted that there are skeptics on the use of DBT instead of 2D mammography, arguing that it leads to overdiagnosis of breast cancer. But this study could sway some doubters.
The results showed that digital mammography and DBT had similar rates of detection for some of the subtypes of breast cancer—the ratio of invasive cancer to ductal carcinoma in situ (DCIS) did not differ much between the two screening methods.
“We found that digital mammography and DBT screening mammography found the same types of cancers, but at different stages,” Philpotts said. “DBT found more aggressive cancers at an earlier stage compared to digital mammography.”
The result showed that DBT had a higher cancer detection rate of 5.3 percent compared with 4.0 percent for mammography. The fact that DBT had a lower rate of detection of advanced cancers—32.7 percent versus 43.6 percent for mammography—indicates that DBT is likely detecting cancers earlier. Further, cancer detection was improved when women had more than one DBT screening.
Another important finding was that the recall rate for additional testing is much lower for DBT than it is for mammography (7.2 percent versus 10.6 percent).
“DBT’s lower recall rate, higher cancer detection rate, and lower rate of advanced cancers is a win, win, win. I think this data will contribute to the debate of overdiagnosis by demonstrating that DBT is not over-diagnosing cancers,” Philpotts said. “Our results may provide healthcare institutions that have not yet switched from digital mammography to DBT with the data they need to adopt the newer technology.”
