Gaglioti, Anne H.

Abstract Background: Racial disparities in breast cancer outcomes persist in the US, in which black women are more likely to die from breast cancer than white women. Despite levels of mammographic screening comparable to the US, Atlanta has a disproportionate burden of late-stage breast tumors and higher mortality rates, especially among black women. To better understand this disparity, we sought to identify tumor, treatment, and patient characteristics that may contribute to the observed differences in breast cancer mortality between black and white women in the metropolitan Atlanta area. Methods: In this study, patients were identified from the Georgia Cancer Registry. We included 4943 non-Hispanic white and 3580 non-Hispanic black women with an initial diagnosis of stage I-IV primary breast cancer between January 2010 and December 2014 in Atlanta. Cox proportional hazard regression was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) to compare black vs. white breast cancer mortality by tumor (stage, grade, ER status, and molecular subtype), treatment (surgery type, receipt of chemotherapy, radiation, hormone therapy, and trastuzumab), and patient (insurance, marital status, SES, and location of service) characteristics. We performed a mediation analysis to evaluate the contribution of subtype, stage, and socioeconomic status (SES) as mediators on the path between race and breast cancer mortality. Results: Compared with white breast cancer patients, black women were younger with tumors that were higher stage, higher grade, and more likely to be larger, node positive and triple negative. In fully adjusted models, black women diagnosed with Luminal A subtype were 58% more likely to die of breast cancer compared to their white counterparts (HR=1.58, 95%CI 1.31-2.00). Similarly, black women with private insurance were 60% more likely to die of breast cancer (HR=1.61, 95%CI 1.25-1.98), and black women in the highest SES group were more than twice as likely to die from breast cancer (HR=2.26, 95%CI 1.26-4.06) than white women with comparable SES. The smallest disparities in breast cancer mortality by race were observed among women without insurance, in the lowest SES index, or those diagnosed with triple-negative breast cancer. The mediation analysis showed 84.8% of the effect between race and breast cancer mortality was through stage, subtype, and SES. Conclusion: Our results indicate variation in racial disparities in breast cancer mortality by tumor and patient characteristics. Consistent with previous reports, our mediation results suggest that later stage and triple-negative subtype among black women are major contributors of the observed disparity. However, our results also shed new light on the disparity, suggesting that the largest disparities are observed among women with ER+ tumors amenable to adjuvant therapies and are most pronounced among women of high SES. More research is needed to understand the drivers of disparities in these treatable tumors. Citation Format: Lindsay J. Collin, Renjian Jiang, Kevin C. Ward, Keerthi Gogineni, Preeti D. Subhedar, Mark Sherman, Mia M. Gaudet, Carmen Radecki Breitkopf, Olivia D'Angelo, Sheryl Gabram-Mendola, Jolie Siegel, Rana Aneja, Anne Gaglioti, Lauren E. McCullough. Identification of factors contributing to breast cancer mortality disparities in the metropolitan Atlanta area [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C053.

AbstractBackgroundRacial disparities in breast cancer (BC) outcomes persist where non-Hispanic black (NHB) women are more likely to die from BC than non-Hispanic white (NHW) women, and the extent of this disparity varies geographically. We evaluated tumor, treatment, and patient characteristics that contribute to racial differences in BC mortality in Atlanta, Georgia, where the disparity was previously characterized as especially large.MethodsWe identified 4943 NHW and 3580 NHB women in the Georgia Cancer Registry with stage I–IV BC diagnoses in Atlanta (2010–2014). We used Cox proportional hazard regression to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) comparing NHB vs NHW BC mortality by tumor, treatment, and patient characteristics on the additive and multiplicative scales. We additionally estimated the mediating effects of these characteristics on the association between race and BC mortality.ResultsAt diagnosis, NHB women were younger—with higher stage, node-positive, and triple-negative tumors relative to NHW women. In age-adjusted models, NHB women with luminal A disease had a 2.43 times higher rate of BC mortality compared to their NHW counterparts (95% CI = 1.99 to 2.97). High socioeconomic status (SES) NHB women had more than twice the mortality rates than their white counterparts (HR = 2.67, 95% CI = 1.65 to 4.33). Racial disparities among women without insurance, in the lowest SES index, or diagnosed with triple-negative BC were less pronounced.ConclusionsIn Atlanta, the largest racial disparities are observed in luminal tumors and most pronounced among women of high SES. More research is needed to understand drivers of disparities within these treatable features.