Access to 3D mammography often depends on race, income and education

A UC Davis Health researcher collaborated on a study exposing stark health disparities in access to 3D mammography.

The study results published in JAMA Network Open today show Black women and Latinas as well as less-educated and lower-income women have not been able to obtain 3D mammography as easily as white, well-educated and higher-income women.

The research team reviewed 2.3 million breast screening exams collected by the national Breast Cancer Surveillance Consortium from 92 imaging facilities across five states. That makes it the largest-ever study of U.S. access to digital breast tomosynthesis (DBT), commonly referred to as 3D mammography. The exams were performed between January 2011 through December 2017.

The 3D technology is more accurate than traditional digital mammography. It can detect more cancers and yields fewer false positives. The study showed access to the breast screening technology has not been equitable, even though it was approved by the Food and Drug Administration a decade ago.

“Given the large research sample and our longitudinal data collection, we were able to evaluate use by minority and traditionally underserved populations,” said UC Davis Professor Diana Miglioretti, the senior author of the paper. “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 were less likely to receive a 3D mammogram.”

3D mammography access isn’t the same for everyone

In 2011, only 3% of women in the study could access 3D mammography at the time of their breast cancer screening. By 2017, that figure had grown to 82%. Unfortunately, this improved availability was not experienced equally. When both 2D and 3D mammograms were available onsite at the time of breast cancer screening, DBT was obtained by:

• 37% of Black women vs. 43% of Asian-American women, 44% of Hispanic women and 53% of white women.
• 41% of women with less than a high school education vs. 50% of women with a college degree.
• 44% of women living in zip codes with the lowest quartile of median household income vs. 51% of women living in zip codes with the highest quartile of median household income.

“The women with poorer access to 3D are already traditionally underserved and more at risk for greater morbidity and mortality from breast cancer,” said Christoph Lee, professor of radiology at the University of Washington School of Medicine and lead author of the paper.

Underlying disparities may prevent access to the most advanced breast screenings

The study did not address whether structural racism in health care or out-of-pocket costs might contribute to the lower access, but Lee and Miglioretti said they can be real barriers.

The authors also say women with higher education might have more opportunity to explore health care options and to know about 3D mammography’s benefits and might seek facilities where 3D mammography is available and perhaps even ask for it directly.

Surprisingly, facility location – urban vs. rural – was not a major factor of 3D mammography availability. This is likely because rural facilities tend to be smaller, with only one standard mammography machine. When this machine is replaced it with a 3D unit, it automatically gives their entire patient population access to 3D mammography. That’s in contrast to urban facilities that usually have a larger number of digital units but often only replace one at a time with 3D-capable units—so some women get 3D, but others might not.

“Women of color already face health inequities when it comes to breast cancer screenings and limiting access to the latest technology could exacerbate the gap in preventative and diagnostic care,” said Miglioretti.

The study received funding from the National Institutes of Health (National Cancer Institute – PO1CA154292, U54CA163303); the Patient Centered Outcomes Research Institute (PCS-1504-30370); the Agency for Healthcare Research and Quality (R01 HS018366-01A1); the National Institute of General Medical Sciences (P20 GM103644) and the American Cancer Society (MRSG-14-160-01CPHPS), among other organizations.

Coauthors on this study are Weiwei Zhu, Kaiser Permanente Washington Health Research Institute; Tracy Onega, University of Utah, Huntsman Cancer Institute; Louise M. Henderson, University of North Carolina; Karla Kerlikowske, UCSF; Brian L. Sprague, University of Vermont Cancer Center, University of Vermont; Garth H. Rauscher, School of Public Health, University of Illinois at Chicago; Ellen S. O’Meara, Kaiser Permanente Washington Health Research Institute; Anna N.A. Tosteson, The Dartmouth Institute for Health Policy and Clinical Practice and Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth; Jennifer S. Haas, Massachusetts General Hospital, Harvard Medical School; Roberta diFlorio-Alexander, Geisel School of Medicine at Dartmouth; Celia Kaplan, UCSF.