Addition of tomosynthesis to digital mammography increases cancer detection rate

University of TorontoJun 25 2014

The addition of tomosynthesis, a 3-dimensional breast imaging technique, to digital mammography in more than 170,000 examinations was associated with a decrease in the proportion of patients called back for additional imaging and an increase in the cancer detection rate, according to a study in the June 25 issue of JAMA.

Screening mammography has played a key role in reducing breast cancer mortality, although it has drawn criticism for excessive false-positive results, limited sensitivity, and the potential of overdiagnosis of clinically insignificant lesions. In 2011, tomosynthesis was approved by the U.S. Food and Drug Administration to be used in combination with standard digital mammography for breast cancer screening. Single-institution studies have shown that adding tomosynthesis to mammography increases cancer detection and reduces false-positive results, according to background information in the article.

Sarah M. Friedewald, M.D., of Advocate Lutheran General Hospital, Park Ridge, Il., and colleagues conducted a study using data from 13 centers to determine if mammography combined with tomosynthesis improves performance of breast screening programs. A total of 454,850 examinations (n = 281,187 digital mammography; n = 173,663 digital mammography + tomosynthesis) were evaluated.

The primary measured outcomes were recall rate (proportion of patients requiring additional imaging based on a screening examination result), cancer detection rate, positive predictive value for recall (proportion of patients recalled after screening who were diagnosed as having breast cancer) and positive predictive value for biopsy (proportion of patients undergoing biopsies who were diagnosed as having breast cancer).

An analysis of the data indicated that the model-adjusted rates per 1,000 screens were as follows: for recall rate, 107 with digital mammography vs 91 with digital mammography + tomosynthesis (an overall decrease in recall rate of 16 per 1,000 screens); for biopsies, 18.1 with digital mammography vs 19.3 with digital mammography + tomosynthesis; for cancer detection, 4.2 with digital mammography vs 5.4 with digital mammography + tomosynthesis; and for invasive cancer detection, 2.9 with digital mammography vs 4.1 with digital mammography + tomosynthesis.

Adding tomosynthesis increased the positive predictive value for recall from 4.3 percent to 6.4 percent and for biopsy from 24.2 percent to 29.2 percent.

"The success of mammography screening in reducing mortality is predicated on the principle of detecting and treating small, asymptomatic cancers before they have metastasized. Accordingly, the preferential increase in invasive cancer detection with addition of tomosynthesis may be of particular value in optimizing patient outcomes from mammography screening," the authors write.

"The association with fewer unnecessary tests and biopsies, with a simultaneous increase in cancer detection rates, would support the potential benefits of tomosynthesis as a tool for screening. However, assessment for a benefit in clinical outcomes is needed."

There will also be a digital news release available for this study, including the JAMA Report video, embedded and downloadable video, audio files, text, documents, and related links. This content will be available at 3 p.m. CT Tuesday, June 24 at this link.

Editorial: Breast Cancer Screening - Should Tomosynthesis Replace Digital Mammography?

"As Friedewald et al have indicated, tomosynthesis is likely an advance over digital mammography for breast cancer screening, but fundamental questions about screening remain, with all available technologies," write Etta D. Pisano, M.D., of the Medical University of South Carolina, Charleston, and Martin J. Yaffe, Ph.D., of the University of Toronto.

"Breast cancer remains a major public health problem, with approximately 40,000 U.S. women still dying annually. The continuing controversy surrounding the most effective strategy for deploying the various available technologies continues unabated, and clear consensus is lacking on when to screen, how often, and with what tools, or even which screen-detected cancers could be managed more conservatively. Only an appropriately powered multisite controlled clinical trial of modern technology can answer the remaining questions definitively. The time is now for the National Institutes of Health to fund such a much-needed trial to address many of the remaining issues about breast cancer screening."