The disparities in female breast cancer incidence and mortality among racial and ethnic groups is well documented. Studies show that while Black women have a lower incidence of breast cancer compared with White women, they are 41% more likely to die from the disease than White women. Breast cancer incidence and mortality also vary across Asian and Hispanic/Latino populations.

The types of breast cancer diagnosed in women of different races and ethnicities also vary. Non-Hispanic Black women are more likely to be diagnosed with tumors that have poorer prognostic characteristics, including large-size, high-grade, hormone receptor–negative breast cancer; and Hispanic women are more commonly diagnosed with larger breast tumors and regional or distant-stage breast cancer compared with non-Hispanic White women.

Although mammography plays a major role in breast cancer detection, how it may potentially contribute to racial differences in breast cancer characteristics and mortality has not been clear. A new prospective study by Nyante et al published in Cancer Epidemiology, Biomarkers & Prevention evaluating the differences in diagnostic mammography performance based on a woman’s race or ethnicity has found that the accuracy of the test differed across racial and ethnic groups, and varied in several measures of diagnostic performance. Addressing characteristics related to imaging facility and access, rather than personal characteristics, may help reduce some of these disparities, according to the study authors.

Study Methodology

The researchers used data from a collaborative network of breast imaging registries that collect data on breast imaging examinations, breast procedures, and cancer diagnoses occurring among women seen at participating facilities. Their analysis included 267,868 diagnostic mammograms performed at 98 facilities in the Breast Cancer Surveillance Consortium between 2005 and 2017.

The researchers used Breast Imaging and Reporting Data System assessments to identify mammograms that radiologists judged to be likely positive and likely negative. The racial distribution of the women whose mammograms were studied was 70% non-Hispanic White; 13% non-Hispanic Black; 10% Asian/Pacific Islander; and 7% Hispanic.

Mammogram assessments were recorded prospectively, and breast cancers occurring within 1 year were ascertained. Performance statistics were calculated with 95% confidence intervals (CI) for each racial/ethnic group. Multivariable regression was used to control for personal characteristics and imaging facility.

Results

The researchers found among the women studied, the invasive cancer detection rate (iCDR, per 1,000 mammograms) and positive predictive value (PPV2) were 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). Short interval follow-up recommendations were most common among non-Hispanic Black women (31.0%; 95% CI = 30.6%–31.5%) vs other groups (range = 16.6%–23.6%).

False-positive biopsy recommendations were most common among Asian/Pacific Islander women (per 1,000 mammograms =169.2, 95% CI = 164.8–173.7) vs other groups (range = 126.5–136.1). Some differences were explained by adjusting for receipt of diagnostic ultrasound or magnetic resonance imaging for iCDR and imaging facility for short-interval follow-up. The researchers found that other differences changed little after adjustment.

“Diagnostic mammography performance varied across racial/ethnic groups. Addressing characteristics related to imaging facility and access, rather than personal characteristics, may help reduce some of these disparities,” concluded the study authors.

Clinical Significance

According to the study authors, “diagnostic mammography performance studies should include racially and ethnically diverse populations to provide an accurate view of the population-level effects.”

“Examining differences in diagnostic digital mammography performance and tumor characteristic outcomes by race and ethnicity may help us understand why disparities in cancer detection and quality of care persists for some demographic groups,” said corresponding study author Sarah J. Nyante, PhD, Associate Professor of Radiology at the University of North Carolina School of Medicine at Chapel Hill, in a statement.

Disclosure: Funding for this study was provided by the National Cancer Institute, the Patient-Centered Outcomes Research Institute, and the Agency for Health Research and Quality. For full disclosures of the study authors, visit aacrjournals.org/cebp.