Tomosynthesis, a three-dimensional (3D) mammography technique, combined with conventional digital mammography improves cancer detection rates and reduces recall rates compared with digital mammography alone, according to a study published in JAMA.1
The findings may lead to a change in the standard of care for breast cancer screening.
“Single-institution studies have shown that tomosynthesis improves cancer detection, however, they have been small and have not necessarily shown statistical significance,” said lead author Sarah Friedewald, MD, co-medical director and section chief of Breast Imaging at the Caldwell Breast Center at Advocate Lutheran General Hospital in Park Ridge, IL. “We evaluated a large number of patients to determine if tomosynthesis—when added to standard digital mammography—improves cancer detection.”
The researchers compared the results of breast cancer screening before and after the introduction of tomosynthesis at 13 institutions. Altogether, 454,850 screening mammograms were interpreted.
“We found that, when patients were managed with tomosynthesis in combination with digital mammography, more invasive cancers were detected,” Dr. Friedewald explained. “We also found a simultaneous decrease in recall rate, which is unusual in a screening setting.”
More Cancers, Less Unnecessary Testing
The cancer detection rate was 4.2 per 1,000 with digital mammography alone and 5.4 per 1,000 with digital mammography plus tomosynthesis, a relative increase of 29%. Cancer detection rates increased at 12 of the 13 study sites.
The rate of recall for further screening was 107 per 1,000 with digital mammography alone and 91 per 1,000 with digital mammography plus tomosynthesis, a 15% reduction.
The rate of cancer diagnosis in women who were recalled rose from 4.3% with digital mammography alone to 6.4% with digital mammography plus tomosynthesis, an increase of 49%. Thus, tomosynthesis increased the likelihood that women who were recalled underwent further testing for a good reason.
The biopsy rate actually increased when tomosynthesis was introduced, from 18.1 per 1,000 to 19.3 per 1,000, but these extra biopsies were beneficial—the likelihood of a cancer diagnosis in women who underwent biopsy increased by 21% when digital mammography plus tomosynthesis was introduced.
Although conventional digital mammography has played a significant role in reducing mortality from breast cancer, it is known to produce excessive false-positive results and may overdiagnose clinically insignificant lesions, leading to unnecessary treatment. Tomosynthesis is a technique whereby data are acquired from a rotating x-ray source. Algorithms reconstruct the data and digitally process the images into slices at different depths, minimizing the influence of overlapping breast structures.
Use of tomosynthesis approximately doubles the total radiation dose compared with conventional digital mammography.
Tomosynthesis in combination with conventional digital mammography was approved by the US Food and Drug Administration for breast cancer screening in 2011.
“It’s the most exciting improvement to mammography that I have seen in my career, even more important for women than the conversion from film-screen mammography to digital mammography,” said senior author Emily F. Conant, MD, chief of breast imaging at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia. “3D mammography finds more clinically significant breast cancers earlier, which is the key so that women have more treatment options and, ultimately, better health outcomes.”
- Friedewald SM, Rafferty EA, Rose SL, et al. Breast cancer screening using tomosynthesis in combination with digital mammography. JAMA. 2014;311(24):2499-2507.