(RxWiki News) Mammography screenings for breast cancer remain controversial. The technology is famous for producing false positives (something suspicious which turns out to be nothing) and causing undue alarm.
The current systems also miss breast cancers because they can’t always clearly distinguish a tumor from normal tissue.
Most mammography equipment takes two-dimensional (2D) pictures of the breast. Researchers have released results of the effectiveness of combining 2D with 3D mammograms.
The combined technology - called Digital Breast Tomosynthesis (DBT) detected more breast cancers in all age groups than 2D mammograms alone.
The DBT approach also produced fewer false positives than did the traditional mammograms.
"Find out what kind of mammogram you’ll be receiving."
Australian and Italian researchers worked together under the leadership of Associate Professor Nehmat Houssami, MBBS, FAFPHM, at the University of Sydney’s School of Public Health in Australia.
The team examined whether DBT screening was better at detecting cancers and reducing false positives than 2D screening alone.
Daniel B. Kopans, MD, professor of radiology at Harvard Medical School and senior radiologist - the Breast Imaging Division – at Massachusetts General Hospital in Boston, provided excellent perspective as to why traditional mammography misses cancers.
"One of the major problems in conventional mammography (screen/film, or digital) is the fact that normal breast tissues can hide cancers. The shadows of tissues in front and back of a cancer can superimpose over the tumor and make it difficult or impossible to see on a 2D mammogram," Dr. Kopans said.
The other downside of existing mammography technology is finding what looks like a tumor, but turns out to be nothing.
Dr. Kopans explained, "Another problem with conventional 2D mammography is the fact that the normal tissue shadows can superimpose on one another and their combined shadow can mimic a possible cancer leading to a woman being recalled from screening for additional evaluation. DBT eliminates this problem and reduces the likelihood of a recall," said Dr. Kopans, who acknowledged being biased because he is the inventor of this technology.
For the study evaluating DBT effectiveness, nearly 7,300 women, with an average age of 58, were screened with both conventional mammography and DBT.
Digital breast tomosynthesis essentially combines a 2D with a 3D view of the breast. The authors explained that “... several low-dose radiographs are used to reconstruct a pseudo-3D image of the breast.”
The system used for this study takes all of the views images at the same time with one compression.
Researchers detected 59 cancers in the group. The majority of the tumors (39) were found with both the 2D and the DBT. The integrated system spotted 20 cancers that had not been detected with the 2D images.
The DBT mammograms also resulted in fewer false positives – 73 versus 141 in the 2D screenings. However, a total of 181 false positives occurred with both types of screenings, an issue that still needs to be addressed.
Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburgh School of Medicine, told dailyRx, "This study demonstrates that tomosynthesis may allow us to better screen women with breast cancer. It is easier to perform and less expensive than breast MRI, and may serve as a useful adjunct to traditional 2D mammography going forward," Dr. Brufsky said.
Acknowledging that mammograms are controversial, Professor Houssami said, "Irrespective of which side of the mammography screening debate one supports, efforts should be made to investigate methods that enhance the quality of, and hence potential benefit from, mammography screening."
“Our results do not warrant an immediate change to breast-screening practice, instead, they show the urgent need for randomized controlled trials of integrated 2D and 3D versus 2D mammography,” Professor Houssami said in a prepared statement.
"As this study shows, DBT is a better mammogram in allowing more cancers to be detected earlier, and will replace conventional 2D mammography for screening all women beginning at the age of 40," Dr. Kopans said.
This study was published April 24 in The Lancet Oncology. Funding came from the National Breast Cancer Foundation, Australia and National Health.
All but one of the authors disclosed having received assistance from Hologic (Hologic USA; Technologic Italy) in the form of tomosynthesis technology and technical support for the duration of the study, and travel support to attend collaborators’ meetings.
