Abstract B74: Examining racial/ethnic disparities in mammography screening performance in a single, large healthcare organization
Authors: Dabbous Firas M. , Rauscher Garth , Macarol Terry , Khan Jenna , Dolecek Therese , Friedewald Sally , Francois Teena , Summerfelt Tom 
Published: May 2015

Introduction: Screening mammography for early detection of breast cancer is subject to both false positive and false negative results. False positive mammograms subject women to unnecessary diagnostic imaging and biopsies that create a burden to the patient and costs to the health care system. False negative mammograms, on the other hand, result in the diagnosis of an “interval” cancer following symptoms and typically at a later stage than if discovered on the prior screen. Prior studies conducted in metropolitan Chicago suggested that differences in both mammogram image quality and quality of the interpretation of the mammogram might contribute to higher false negative rates (FNR) and higher false positive rates (FPR) for ethnic minority patients. We sought to examine predictors of FNR and FPR, and whether ethnic disparities might exist in these outcomes within a single, large healthcare organization.

Methods: Screening mammograms during 2001-2009 were linked to incident breast cancer cases for the period 2001-2010 from the Illinois State Cancer Registry (ISCR) using probabilistic linkage methods. Screening mammograms were scored by the interpreting radiologist using the American College of Radiology Breast Imaging Reporting and Data System (BIRADS) and each mammogram was defined as negative (BIRADS 1,2) or positive (BIRADS 0,4,5); BIRADS 3 mammograms were excluded from these analyses. A false positive (FP) mammogram was defined as a screening mammogram with an abnormal interpretation which nonetheless did not result in a breast cancer diagnosis in the subsequent 12 months. A false negative (FN) mammogram was defined as a screening mammogram with a normal interpretation in a woman who nonetheless was diagnosed with breast cancer (“interval cancer”) in the subsequent 12 months. We examined patient factors (race/ethnicity, age at diagnosis, and breast density) and tumor characteristics including hormone (estrogen and progesterone) receptor (ER/PR) status, tumor grade, and behavior (in-situ vs. malignant) and their association with FNR and FPR.

Results: A total of 669,222 screens were included in this analysis and 4,058 breast cancer cases were diagnosed in the 12 months subsequent to each screening mammogram (3,071 screen-detected and 988 interval cancers). Overall, the false negative rate was 24.3%. As expected, the FNR decreased with increasing age, and increased with increasing breast density. Also as expected, FNR was higher for ER-/PR- breast cancer than other forms (31% vs. 25%, p=0.01), was higher for high grade/undifferentiated tumors and was higher for malignant than in situ tumors (27% vs. 19%, p &lt;0.001). Contrary to expectation, however, FNR was higher in White than African Americans patients (26% vs. 20%, p&lt;0.001); and FNR was higher for digital than analog mammograms (27% vs. 23%, p=0.001). With regards to false positive rate (FPR), FPR was 12.6% overall. As hypothesized, FPR was slightly higher in African Americans compared to Whites (14% vs. 11%, p=0.014), and higher for mammograms performed on women with heterogeneously/extremely dense versus less dense breasts (14% vs. 11%, p&lt;0.0001).

Conclusion: Contrary to expectation, we did not find a racial disparity in the probability of a false negative mammogram, though we did find a modestly increased false positive rate in ethnic minorities. Radiologists in this organization are provided feedback on the quality of their screening interpretations on a regular basis, and this quality control program may be responsible for leveling the quality of screening mammography by race/ethnicity.

Citation Format: Firas M. Dabbous, Garth Rauscher, Terry Macarol, Jenna Khan, Therese Dolecek, Sally Friedewald, Teena Francois, Tom Summerfelt. Examining racial/ethnic disparities in mammography screening performance in a single, large healthcare organization. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B74. doi:10.1158/1538-7755.DISP13-B74