3D mammograms haven’t yet been proven to be the best screening tool for breast cancer, but more women in the United States are getting them.
From 2015 to 2017, 3D mammography screening increased from 13% of screening examinations to 43%, according to a study published on Monday in the medical journal JAMA Internal Medicine.
“That’s a substantial increase in a two-year period,” said Dr. Ilana Richman, lead author of the study and an assistant professor in general internal medicine at Yale School of Medicine. “The technology has become really popular.”
A mammogram is an X-ray picture of the breast. In 3D mammography, also known as digital breast tomosynthesis, a scan takes X-rays from multiple angles to create a 3D image of the breast. Standard 2D mammography takes images only from the front and side of the breast.
Researchers found that the popularity of 3D mammography wasn’t growing in all areas of the country. The combination of 2D and 3D mammography was more popular and grew faster in Northeast and Northwest regions of the United States, while Southeast regions showed slower growth and overall use. Screening with both 3D mammography and 2D mammography was the most common method of screening in less than 5% of regions in 2015, but grew to be the most common in 42% of regions by 2017.
In regions with high use of 3D mammography, residents were more likely to be wealthy, educated and white.
“This is what we’ve been expecting to see for a long time,” said Robert Smith, vice president of cancer screening for the American Cancer Society. Smith was not involved in the study. “When you roll out new, higher technology and more expensive equipment, the early adopters are generally going to be in more affluent parts of the country.”
In areas with the highest 3D mammography growth and use, the average income of residents was $53, 835; in areas with the slowest growth and use, the average income was $45,254. The regions with high 3D mammography use also had a higher percentage of white residents (82.2% versus 70.5%) and lower percentage of black residents (5.3% versus 18.6%).
Although more research is needed to show the effectiveness of 3D mammography, these regional differences “could worsen existing disparities in breast cancer outcomes,” wrote Dr. Joy Melnikow and Dr. Joshua Fenton in a response to the study, also published in JAMA Internal Medicine.
The health disparities were found at a population level, not an individual level, so we don’t know whether the wealthier and more educated women in these regions were the same individuals who got 3D mammography, Richman said.
Researchers collected data on 9.7 million breast screening exams from 2015 to 2017 among women in the United States between the ages 40 and 74. The breast screening exam data came from the Blue Cross Blue Shield Axis, a database containing insurance claims. The researchers also compared the data geographically and got demographic information from the 2015 US Census Bureau American Community Survey and 2010 US Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance Survey.
The 3D mammography trends from the Blue Cross Blue Shield claims were also compared with Medicare data. There weren’t significant differences in the pattern of 3D mammography use between the two groups, according to the study.
How mammograms differ
In standard 2D mammography, normal tissues can overlap and falsely look like a mass because of the nature of two dimensional pictures. But the cost and amount of radiation are higher for 3D mammogram than 2D mammograms, according to the National Cancer Institute.
“The dose from these mammography exposures is very low, and therefore the true possibility that these additional exposures could cause measurable harm also is low,” Smith wrote in an email. “As for costs, it seems more and more insurance is covering 3D, so cost likely will be less of an issue over time.”
Both 2D and 3D mammography can identify breast cancer and early studies have shown that 3D mammography reduces how many women need to get more testing because of a suspicious finding, according to Richman. This is “one compelling reason for patients” to get 3D mammography and may be why there’s been a “rapid uptake,” she said.
However, 3D mammography is not currently recommended by the US Preventive Services Task Force for routine breast cancer screening. Without these clinical guidelines, the US Food and Drug Administration requires that for a patient to get 3D mammography, they need to get it alongside the standard 2D mammography, Smith said. The FDA certifies facilities to perform mammography and must approve new breast imaging equipment before it can be sold in the United States.
“We don’t have enough data to say it’s definitely better … over 2D,” Smith said, but 3D mammography does seem to be getting more popular.
“This study shows how technology in the early phase is taking off,” Richman said.