Race, Lower Income, Less Education Reduce DBT Access

3D mammography is not equally accessible to all women. Women who come from racial or ethnic minority groups, women who are less educated, and women who have lower incomes are less likely to undergo the exam that is most likely to detect an existing breast cancer without raising a false red flag.

In a five-state study, including nearly 100 facilities, a multi-institutional team showed that less than half of women in these groups have access to this type of breast cancer screening.

“This study was about whether adoption of this technology is equitable. We’re showing that it has not been, even though it has been FDA-approved for a decade now,” said lead study author Christoph Lee, M.D., MS, MBA, professor of radiology from the University of Washington School of Medicine. “Black and Hispanic women, and less-educated and lower-income women have not been able to obtain 3D mammography as easily as white, well-educated, and higher-income women.”

Lee’s team published their findings on Feb. 19 in JAMA Network Open.

Digital breast tomosynthesis (DBT) has been a viable alternative to digital mammography since it received approval from the U.S. Food & Drug Administration in February 2011. In the intervening years, a plethora of studies have shown that DBT is actually more accurate than digital mammography and does a better job at detecting breast cancer with fewer false positives.

Related Content: Digital Breast Tomosynthesis on Track to Replace Digital Mammography

For this study, the team examined 2.3 billion breast screening exams that were pulled from the Breast Cancer Surveillance Consortium. Patients, who were screened between January 2011 and December 2017, came from 92 imaging facilities across five states. With this volume, the team said, it is the largest study, to date, to analyze the access women have to DBT throughout the United States. In addition to looking at whether access was equitable among all women, the team also assessed whether facilities offered DBT at the time a patient was screened and compared DBT and mammography use at each facility across patient populations.

Their findings showed that DBT use and access did change over time. At the start of the study in 2011, only 3 percent of women included had access to DBT. By 2017, more facilities were using the technology, and 82 percent of women had access – but, it was not equal across all groups.

“Given the large research sample and our longitudinal data collection, we were able to evaluate use by minority and traditionally underserved populations,” said senior author Diana Miglioretti, Ph.D., professor and division chief of biostatistics from the University of California Davis. “Unfortunately, we were not surprised to find that these traditionally underserved populations were less likely to attend facilities that offered 3D mammography, and even when they did, they less likely to receive a 3D mammogram.”

According to their analysis – when both 2D and 3D mammograms were available – DBT was utilized by fewer than 50 percent of women who were in racial and ethnic minority groups, as well as those who were less educated and those who were of lower income.

Specifically, a DBT scan was provided to:

• 37 percent of African American women, 43 percent of Asian-American women, and 44 of Hispanic women versus 53 percent of white women
• 41 percent of women with less than a high school education compared to 50 percent of women who had earned a college degree
• 44 percent of women living in zip codes that had the lowest 25 percent of median household incomes versus 51 percent of women who lived in zip codes with the highest 25 percent of median household incomes

These results are critical, Lee said, because women with less access to 3D screening are already traditionally underserved, putting them at a greater risk of breast cancer morbidity and mortality.

Assessing the Barriers

Although addressing whether the institutional barriers to care, such as structural racism or cost, contributed to decreased access to newer technologies was outside the scope of the study, the team acknowledged that these obstacles are real and likely played into the inequity.

For example, Lee said, because DBT generates digital slices of breast tissue, acquisition and interpretation time are longer, and the cost is higher. While some states, including Washington, have laws in place that prevent charging patients more for DBT, most states do not. Consequently, depending on the type of insurance a patient has, she may have to pay high out-of-pocket costs for a 3D mammogram.

Additionally, a woman’s education could impact how much she knows about DBT mammography and the benefits it can provide. Women who have higher education levels could be more likely to explore healthcare options, to research the possible benefits of 3D mammography, or to search for a facility that offers the technology. They could also be more likely to directly ask for the service.

The physical availability of the technology also played a role. While approximately 40 percent of all certified mammography units actually have DBT capability, more than two-thirds of breast imaging facilities offer DBT in at least one of their units, according to FDA data. In addition, urban or rural location was less important than anticipated, Lee said.

In such situations, he said, a rural site could have one digital mammography machine that would provide access to all patients once switched to DBT. However, urban facilities might have more money to purchase machines, but if it can only afford one 3D-capable unit – at a cost of approximately $750,000 a pop – they will still have to direct some patients to 2D machines. Consequently, some sub-groups of women are not being screened with 3D mammography even when the option technically exists at their imaging facility.

“We’re going in the wrong direction. You have a lot more women in certain subpopulations benefitting from new technologies and other subpopulations not,” he said. “Existing disparities in breast cancer screening outcomes could widen unless these factors are addressed.”

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