Variations in Diagnostic Mammograms Emphasizes Need for Racially and Ethnically Diverse Performance Studies

Sarah J. Nyante, PhD

Characteristics of community-based breast imaging facilities may play a role in addressing disparities in diagnostic mammography performance across different racial and ethnic groups, according to findings from a study recently published Cancer Epidemiology, Biomarkers & Prevention.¹

“Our model-based analysis suggests that imaging facility characteristics may play a role in the higher frequency of short interval follow-up that was observed among non-Hispanic Black women,” Sarah J. Nyante, PhD, assistant professor of radiology, Department of Radiology, at the University of North Carolina at Chapel Hill, and coinvestigations, wrote in the study.“We did not have detailed information on the characteristics of each imaging facility in this study. However, prior studies have shown that Black women are less likely to obtain mammograms at facilities accredited by the National Consortium of Breast Centers or American College of Radiology’s Breast Imaging Center of Excellence programs and therefore may receive a lower quality of care.”

“Diagnostic mammography performance studies should include racially and ethnically diverse populations to include racially and ethnically diverse populations to provide an accurate view of the population–level effects,” they added.

Overall, the invasive cancer detection rate (iCDR) per 1000 mammograms was 70% among non-Hispanic White women, 13% among non-Hispanic Black women, 10% among Asian/Pacific Islander women, and 7% among Hispanic women. The positive predictive value (PPV2) was highest among non-Hispanic White women (iCDR, 35.8; 95% CI, 35.0-36.7; PPV2 27.8; 95% CI, 27.3-28.3) and lowest among Hispanic women (iCDR, 22.3; 95% CI, 20.2-24.6; PPV2, 19.4; 95% CI, 18.0-20.9).

Non-Hispanic Black women were most likely to receive short interval follow-up recommendations (31.0%; 95% CI, 30.6%-31.5%) compared with other groups (range, 16.6%-23.6%). This would require patients to return for additional imaging approximately 6 months following the first assessment. Further, false-positive biopsy recommendations were most common among Asian/Pacific Islander women compared with other groups. Per every 1000 mammograms, 169.2 incidences of false-positive recommendations occurred (95% CI, 164.173.7) compared with other groups (range, 126.5-136.1).

Study authors explained that racial and ethnic differences in breast cancer incidence and mortality are well documented. For example, in the US, the rate of breast cancer incidence is highest and associated mortality rates are known to be highest among non-Hispanic Black women. In contrast, both rates are lowest for Hispanic and Asian/Pacific Islander women.

In addition, the type of diagnoses tends to differ between these groups as well. For instance, non-Hispanic Black women are at an increased risk of receiving a diagnosis of breast cancer with poorer prognostic factors (eg, large tumor size, high grade, hormone receptor–negative status) compared with other groups. Hispanic women are more likely receive a diagnosis of breast cancer with larger, distant-stage or metastatic tumors, than non-Hispanic White women.

Investigators have attempted to uncover the root cause of these difference by studying different risk factors, socioeconomic status, health insurance coverage, provider actions/inaction, access to timely treatment, and access to high-quality care as contributors. However, even after controlling for these factors, the trends remain suggesting that additional factors may be at play.

Investigators therefore conducted a cohort study which assessed 267,868 diagnostic mammograms across 98 facilities in the Breast Cancer Surveillance Consortium between 2005 and 2017. Assessments were recorded prospectively within a year of the mammogram. Investigators calculated performance statistics with 95% confidence intervals for each group and multivariable regression was used to control for personal characteristics and imaging facility.

The findings showed that ultrasound, in addition to mammography, was used to determine the Breast Imaging Reporting and Data System assessment for approximately half of the exams, with Hispanic women representing the highest number of women receiving this assessment strategy (55%) and non-Hispanic Black women representing the lowest (43%).

The cancer detection rate was highest among Asian/Pacific Islander women (54.3 per 1000) and lowest among Hispanic women (32.8 per 1000). Asian/Pacific Islander women also had the highest overall mammogram sensitivity (94.2%; 95% CI, 93.0%-95.3%) and highest false-positive rate (169.2 per 1000; 95% CI, 164.8-173.7). In comparison, non-Hispanic Black women had the highest false-negative rate overall (4.6 per 1000; 95% CI, 3.9-5.4).

Ultimately, the location of the mammogram was deemed to be the key factor in determining if a woman received an ultrasound and/or an MRI during the diagnostic work-up and imaging. After adjusting for ultrasound and/or MRI, the reduced difference in cancer detection rates between Black and White patients was model 7 odds ratio (OR), 0.84 (95% CI, 0.79-0.90) vs model 8 OR, 0.98 (95% CI, 0.91-1.05). Moreover, adjustments for imaging facility further attenuate the differences in the short interval follow-up recommendations—model 8 OR, 1.39; (95% CI, 1.35-1.43) vs model 9 OR, 1.03 (95% CI, 0.99-1.07). Adjustment for other factors did not yield any explanation for the racial/ethnic differences in mammography performance.

The study authors concluded that the results suggest non-Hispanic Black women may be at risk of more potential harm related to diagnostic mammography than other groups.

“Exams conducted among non-Hispanic Black women had the lowest sensitivity and highest false-negative rate, indicating that this group may experience a delayed diagnosis more often.”

“Our findings indicate that factors associated with the imaging facility, rather than individual characteristics, may explain some of these differences, [because] the study population consisted of women who had already received a screening mammogram.”

These findings underscore the need to ensure that sufficient racial and ethnic diversity are present in studies which determine mammography recommendations, they concluded.

Reference

Nyante SJ, Abraham L, Aiello Bowles EJ, et al; Breast Cancer Surveillance Consortium. Diagnostic mammography performance across racial and ethnic groups in a national network of community-based breast imaging facilities. Cancer Epidemiol Biomarkers Prev. Published online June 17, 2022. doi:10.1158/1055-9965.EPI-21-1379