Introduction: Breast cancer (BC) is the second leading cause of female cancer-related mortality in the United States. Despite advances in therapies which have significantly lowered BC mortality rates over the years, the decline in mortality in African American/Black women continues to lag behind. Black women with BC continue to do poorly compared to non-Hispanic White women. The etiologies underlying this disparity are multifactorial and still remain unclear. Our study aims to investigate the differences in clinical and socioeconomic characteristics (cts) between Blacks and Whites and evaluate their prognostic value on long-term outcomes. Methods: We conducted a retrospective, population-based analysis utilizing the Surveillance, Epidemiology, and End Results (SEER) database, and studied BC pts from 1975-2017. Different demographic and clinical cts were analyzed by race. Univariate (UV) and multivariable (MV) analyses were performed to evaluate the associations of race with disease-specific survival (DSS), overall survival (OS) using Cox regression models. Results: A total of 816,763 pts were analyzed (n=720,144 White, n=966,19 Black). As compared to White BC patients (pts), Black pts were younger in age (median age 57 years vs. 62 years), with a higher tumor stage (III/IV; 25% vs. 16.3%) and a higher tumor grade (III/IV; 52.2% vs. 35.3%) at disease presentation (p<0.001). Furthermore, Black pts were more likely to present with triple-negative (23.9% vs. 11.1%) and Her-2+ BC (20.6% vs. 16.3%) than White pts (p<0.001). Black pts were also more likely to be uninsured (3.4% vs.1.1%), single (64.3% vs. 42.5%), and less likely to receive breast surgery (90.7% vs. 95.4%) as compared to White pts (p<0.001). A higher proportion of Black pts lived in urban areas (93.9% vs. 87.9%) and had a higher county-level availability of hospitals with oncology services per million population (median 126 vs. 120.6) than White pts (p<0.001). Black pts had a worse DSS (Hazard Ratio (HR) 1.68, 95% CI 1.66-1.71)) and OS (HR 1.30, 95% CI 1.29-1.31) compared to White pts (p<0.001). The racial differences in DSS and OS remained significant on both UV and MV analyses while controlling for each demographic and clinical variable. Conclusions: Our study confirms that Black pts with BC have a worse OS and DSS as compared to White pts. These disparities could be partially explained by observed differences in underlying aggressive tumor biology (stage, grade, hormone receptor status, age at diagnosis), lower access to health care (insurance status and % receiving breast surgery) and weaker social support systems (% single). However, the fact that the survival disparity persisted even after controlling for these factors suggests that there are potentially more variables driving these racial differences in breast cancer outcomes. We note that more Black pts resided in UA and had access to hospitals with oncology services reflecting that there could be disparities in health care utilization patterns. Further studies investigating these variables would be of paramount importance in order to identify underlying causes for poorer outcomes in Black pts and help eliminate this survival gap.
Citation Format: Medhavi Gupta, Rohit Gosain, Maithreyi Sarma, Stuthi Perimbeti, Kristopher Attwood, Wenyan Ji, Shipra Gandhi, Yara Abdou. Racial disparities in breast cancer outcomes: A SEER population based study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-29.