Study: 3-D Mammography Detects More Invasive Cancers
The test also reduced call-back rates
Three-D mammography — known as digital breast tomosynthesis — found significantly more invasive cancers than a traditional mammogram alone and reduced call-backs for additional imaging, according to a study of nearly half a million women.
The largest study to date measuring the effectiveness of the technology, reported in the Journal of the American Medical Association, could lead to a change in the standard of care for breast screening.
In the retrospective study, the researchers looked at 281,187 digital mammography examinations and 173,663 examinations with both tomosynthesis and digital mammography between 2010 and 2012. The data set included women from a wide range of breast cancer screening programs that were both geographically diverse and included both academic and community practices, 13 in total.
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 versus 91 with digital mammography plus tomosynthesis (an overall decrease in recall rate of 16 per 1,000 screens); for biopsies, 18.1 with digital mammography versus 19.3 with digital mammography plus tomosynthesis; for cancer detection, 4.2 with digital mammography versus 5.4 with digital mammography plus tomosynthesis; and for invasive cancer detection, 2.9 with digital mammography versus 4.1 with digital mammography plus tomosynthesis.
Adding tomosynthesis increased the positive predictive value for recall from 4.3% to 6.4% and for biopsy from 24.2% to 29.2%.
Conventional digital mammography is the most widely used screening modality for breast cancer, but may yield suspicious findings that turn out not to be cancer, so-called false positives. Such findings are associated with a higher recall rate.
Tomosynthesis, however, allows for 3-D reconstruction of the breast tissue, giving radiologists a clearer view of the overlapping slices of breast tissue. A relatively new technology, it has shown promise at reducing recall rates in all groups of patients, including younger women and those with dense breast tissue, and better detection rates in smaller studies. In 2011, the FDA approved tomosynthesis to be used in combination with standard digital mammography for breast cancer screening.
Three-D mammography is the only method used for breast cancer imaging that has demonstrated this combined benefit, the authors report. While 3-D mammography found more invasive cancers, detection of in situ cancers (non-invasive cancers) was similar to a traditional mammography.