Huge Study Shows 3D Mammograms Better Than 2D
A 3D mammogram finds more breast cancers and has a lower false-positive rate than a 2D mammogram, according to a study of more than 1 million women.
The research was published online on March 14, 2023, by the journal Radiology. Read “Mammographic Screening in Routine Practice: Multisite Study of Digital Breast Tomosynthesis and Digital Mammography Screenings.”
About 3D mammograms
A 3D mammogram — also called digital breast tomosynthesis, digital tomosynthesis, or just tomosynthesis — creates a 3D picture of the breast using X-rays. Several images from different angles around the breast are used to create the 3D picture.
A traditional mammogram creates a 2D image of the breast using two X-ray images of each breast.
In 2011, 3D mammography was approved by the U.S. Food and Drug Administration (FDA) and later became a standard of care for breast cancer screening. Still, 3D mammography may not be available at all hospitals and mammogram facilities.
To start offering 3D mammograms, facilities must buy new mammography machines or update their existing machines to make them 3D-capable. Not all facilities have been able to make the switch to 3D mammography because of large up-front costs for equipment. In other cases, facilities that have rental agreements for 2D mammography equipment must wait until those leases end before they can upgrade.
According to statistics from the FDA from March 1, 2023, about 85% of U.S. screening facilities offer 3D mammograms in at least one of their mammography units, but fewer than half of all accredited units are actually 3D-capable.
A number of studies have found that 3D mammograms find more cancers than traditional 2D mammograms and that they also reduce the number of false positives.
A false positive is when a mammogram shows an abnormal area that looks like a cancer but turns out to be normal. Ultimately, the news is good: no breast cancer. But the suspicious area usually requires follow-up with more than one doctor, extra tests, and extra procedures, including a possible biopsy. There are psychological, physical, and economic costs that come with a false positive.
About the study
Many of the earlier studies showing 3D mammograms were better than 2D mammograms focused on specific factors, such as finding cancer in dense breasts or detecting advanced-stage breast cancers. In this study, the researchers wanted to see how 3D mammograms compared with 2D mammograms in a large group of U.S. women having routine screening mammograms.
The study included information from more than 1.1 million women ages 40 to 79 who were part of five large healthcare systems across the United States. None of the women had a history of breast cancer.
Between January 2014 and December 2020:
597,947 women had 1,693,727 3D mammograms
502,500 women had 834,336 2D mammograms
The recall rate for all the women in the study was 9.4%. This means that 9.4% of the women were called back for more testing after a mammogram. Recall rates were:
8.9% for 3D mammograms
10.3% for 2D mammograms
This difference was statistically significant, which means that it was likely due to the difference in mammogram technique, rather than just because of chance.
Also, when women who had a 3D mammogram were called back for more testing, it was less likely to be a false positive result than when women who had a 2D mammogram were called back.
Overall, 9,714 cancers were found:
3D mammograms found 6,293 cancers
2D mammograms found 3,421 cancers
The cancer detection rate per 1,000 women screened was higher for 3D mammograms:
3D mammograms found 5.3 cancers per 1,000 women screened
2D mammograms found 4.5 cancers per 1,000 women screened
This difference also was statistically significant.
“We showed that the most important mammographic screening outcomes, increased cancer detection combined with fewer false positives, were significantly improved when women were screened with digital breast tomosynthesis compared to 2D digital mammography alone,” co-author Emily F. Conant, MD, professor of radiology and chief of the Division of Breast Imaging at the Hospital at the University of Pennsylvania, said in a statement. “Therefore, women should seek out sites that routinely offer breast cancer screening with [3D mammograms].”
Dr. Conant also is a member of the Breastcancer.org Professional Advisory Board.
What this means for you
If you aren’t sure whether your screening facility offers 3D mammograms, call and check before you make your appointment. If the facility doesn’t offer 3D mammograms, ask your doctor to recommend a facility that does.
If you aren’t sure whether your insurance plan covers 3D mammograms, call and ask. Both Medicare and Medicaid cover 3D mammograms.
In some states, such as Washington, there are laws that require facilities not to charge more for 3D mammograms. So even if your insurance doesn’t cover a 3D mammogram, you can still get one for the cost of a 2D mammogram, which in almost all states is free. In other states, such as New Jersey and Pennsylvania, there are laws that require insurers to cover 3D mammograms at no cost to women.
If you’re unsure about how much, if anything, you have to pay for a 3D mammogram, call the facility and ask.
Learn more about 3D mammograms.
— Last updated on May 25, 2023 at 2:02 PM