According to a new study, you're not likely to benefit from having a 3D mammogram unless you have dense breast tissue and a higher risk of developing breast cancer.
Digital breast tomosynthesis (DBT) is the technical term for 3D mammograms. Karla Kerlikowske, MD, a lead author of the study and a professor in the Department of Medicine and Epidemiology and Biostatistics at the University of California, San Francisco, told Verywell that DBT uses low-dose X-rays to get views of the breast from different angles and assembles 3D images.
“The 3D is almost like a CT [computed tomography scan] of the breast,” said Kerlikowske. “You are looking at slices through the breast.”
While it's high-tech, the researchers found that most people in the study did not benefit from 3D mammograms over the standard 2D technique.
Kerlikowske said that when 3D mammograms first became available in 2011, they were only required if a person's dense breast tissue made the 2D screening less helpful or if something was seen on the 2D screening required follow-up.
The double screening meant that patients got a double dose of radiation. However, both doses were small.
According to Kerlikowske, the study showed there were no risks of using 3D mammography compared to 2D mammography, even though the benefits were small.
The study suggests people with a high risk of breast cancer and extremely dense breasts benefit from 3D mammograms the most.
Some people are more likely to have dense breast tissue, including younger people, people taking hormone replacement therapy, people who are pregnant or breastfeeding, and people with less body fat.
To come to this conclusion, researchers used records from 504,427 women who had screening mammograms between 2011 and 2018 at 44 U.S. Breast Cancer Surveillance Consortium facilities.
The women in the study were between the ages of 40 and 79 years old. Some of them had only 2D mammograms, some had only 3D mammograms, and some had both.
The researchers compared the rates of interval cancer and advanced cancer for each kind of mammogram.
In an editorial published with the study, the authors explained that interval breast cancer is one that is found during screening but that was not seen (or was not visible) during a previous screening. The authors wrote that “in essence, interval cancers are a result of screening failures."
The researchers found that:
Where was there a difference? The 3.6% of women in the study who had extremely dense breasts and a high risk of breast cancer had a lower risk of advanced-stage cancer if they had received 3D mammograms instead of 2D mammograms.
Stamatia Destounis, MD, FACR, a spokesperson for the American College of Radiology (ACR) and chair of the ACR's Breast Imaging Commission, told Verywell that the study showed that patients who had 3D mammograms instead of traditional digital mammography had a lower false-positive rate (when the screening shows something but no cancer is found).
Fewer false-positive results could mean less anxiety for patients about a possible cancer diagnosis and fewer breast biopsies or other diagnostic tests, but the researchers did not consider the finding to be statistically significant.
Destounis, who was not involved with the research, said that other studies have shown that 3D mammograms can reduce call-backs for more screening and short-term follow-ups, which are “overall, all good points and positives for DBT.”
Even if most patients don't need a 3D mammogram, having the ability to offer one to the patients who would is important.
Destounis said that today, most mammography facilities have at least one DBT unit for 3D mammograms and that there are nearly 11,000 such units in the United States (out of just over 24,000 total mammography units).
Both Destounis and Kerlikowske said that many centers are transitioning to 3D mammography as their older technology wears out and needs to be replaced.
A DBT imaging machine can be a good investment for providers who want to keep pace with their patients' needs and preferences. Kerlikowske said that if it's set to do so at the time of an exam, the DBT machine can be also used to create 2D digital mammograms.
“There are some women who only want the 2D for different reasons," said Kerlikowske. "One is that some insurance companies charge a copay for 3D and it's up to $50.”
According to Kerlikowske, health insurance companies are required by the Affordable Care Act (ACA) to cover screening mammograms with no copay, but some only offer that for 2D mammograms.
If you have dense breast tissue and a higher risk of developing breast cancer, you may benefit from having a 3D mammogram.
If you have dense breasts and a low-to-average risk of breast cancer, research has shown that you probably won't get more benefit from a 3D mammogram than you would from a standard 2D mammogram.