Diagnostic mammography performance varied across racial and ethnic groups based on a study conducted by researchers at UNC Lineberger Comprehensive Cancer Center. The overall impact of the multi-institutional study showed that diagnostic mammography studies should include racially and ethnically diverse populations to provide an accurate view of the population-level effects (Cancer Epidemiol Biomarkers Prev 2022; doi: 10.1158/1055-9965.EPI-21-1379).
"We evaluated differences in diagnostic mammography performance based on women's race/ethnicity," said Sarah J. Nyante, PhD, MSPH, Associate Professor of Radiology at the UNC School of Medicine, as well as Adjunct Assistant Professor of Epidemiology at the UNC Gillings School of Global Public Health. "The study assessed diverse populations to identify how mammography performance can vary among differing groups."
Highlights of the study showed two factors that may lead to some disparities were radiology facilities and imaging process. Research also showed the rate of diagnostic accuracy highest in non-Hispanic White women and lowest in Hispanic women.
"Our study is documenting differences in outcomes while providing an understanding of how we can improve the science and in delivering equitable health care," Nyante stated. "As a secondary analysis, we looked at the performance differences to determine if there are factors that may explain these differences."
This secondary analysis suggested that addressing characteristics related to the imaging facility and access, rather than personal characteristics, may help reduce some of the disparities.
"We used statistical models to adjust for factors, such as age, to see if the differences could be removed if we held those factors constant," she noted. "We found that personal characteristics did not influence disparities."
Two factors did impact disparities-the radiology facility and the imaging process, based on whether a diagnostic MRI or a sonogram, in addition to the mammogram.
"However, the disparities...did not fully explain the differences," said Nyante. "More research is needed to analyze the characteristics of each facility to reach a conclusion. This is just the tip of the iceberg."
Methodology & Results
The researchers reviewed 267,868 diagnostic mammograms from women with a prior abnormal screening result; women were followed for 1 year after their mammogram to see if they developed breast cancer. The records came from 98 facilities in the Breast Cancer Surveillance Consortium, a mix of urban and rural locations spanning six states, including the Carolina Mammography Registry, and were based on mammograms performed from 2005 to 2017.
The invasive breast cancer detection rate was highest in non-Hispanic White women (35.8 per 1,000 mammograms) and lowest among Hispanic women (22.3 per 1,000 mammograms). A recommendation for short interval follow-up, which entails additional imaging after 6 months, was most common among non-Hispanic Black women (31%).
"Even though we found differences between racial and ethnic groups that we evaluated, none of the mammogram practices fell below the minimal acceptable standards for diagnostic interpretation that were published in 2013," said Nyante.
She emphasized that the results describe what is happening at the population level, as opposed to individual outcomes. "The average outcome in a particular group does not mean the equivalent for an individual, but speaks to the average outcome of that group."
Nyante noted that one of the unexpected findings from the research was the high proportion of ductal carcinoma in situ diagnoses in Asian/Pacific Island women.
Future Studies
While the current study looked at the impact of diagnostic mammography, future studies will look at diagnostic performance among women who had a diagnostic mammogram because they had breast symptoms, according to Nyante. "Some differences were explained by adjusting for receipt of diagnostic ultrasound or MRI for iCDR and imaging facility for short-interval follow-up. Other differences changed little after adjustment."
Currently, many mammograms now utilize three-dimensional imaging, whereas, for the time frame of this study, most mammograms were two-dimensional, making generalizations to current practice unclear and a factor that the researchers hope to follow up on in future research.
"In future studies, we'd like to develop a follow-up study where we can really dig into the factors that influence the disparities," Nyante said.
Amy Gallagher is a contributing writer.
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