Abstract PD1-05: Racial/Ethnic Segregation and Inequities in Metastatic Breast Cancer Treatment Initiation and Overall Survival
Authors: Guadamuz Jenny S. , Calip Gregory S. , Asfaw Alemseged A. , Wang Xiaoliang , Pittell Harlan , Kaur Maneet , Pierre Amy E. , Ryals Cleo A. 
Published: March 2023

Abstract
Background While racial/ethnic segregation, a form of structural racism, has been linked to health inequities, there is limited information regarding segregation and its potential impact on breast cancer care and outcomes. Here we assessed whether and to what extent racial/ethnic segregation is associated with timeliness of care and real-world overall survival (rwOS) in patients diagnosed with metastatic breast cancer (mBC). Methods This retrospective study used the nationwide Flatiron Health electronic health record-derived de-identified database. The cohort included community oncology patients (≥ 18 years) diagnosed with mBC between January 2011 and April 2022. Census tract data from the American Community Survey (2015-2019) was used to characterize neighborhoods based on the most recent recorded patient address. Segregation was defined as predominant race/ethnicity (e.g., tracts whose population was ≥ 50% non-Latinx Black were labeled as predominantly Black neighborhoods). Timeliness of care was defined as biomarker (estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2) testing within 30 days and systemic treatment initiation within 60 days of metastatic diagnosis (evaluated using Χ2 tests). We estimated Cox proportional hazard models adjusted for age and sex to examine rwOS (patients were followed from diagnosis to death or last recorded activity). Results Among 18,884 patients diagnosed with mBC (median age: 65 years), 71.0% lived in predominantly White neighborhoods, 7.5% in Black neighborhoods, and 8.7% in Latinx neighborhoods. Compared with patients residing in predominantly White neighborhoods, patients in Black and Latinx neighborhoods were more likely to be diagnosed with de novo mBC (30.7% vs. 34.8% and 33.5%, respectively) and have Medicaid (7.6% vs. 15.8% and 15.3%). Fewer patients in predominantly Black (74.4%) and Latinx (69.9%) neighborhoods received timely biomarker testing compared to patients in White (77.7%) neighborhoods (p &lt;.01). Similarly, fewer patients in predominantly Black (73.5%) and Latinx (72.6%) neighborhoods had timely treatment initiation compared to patients in White (79.6%) neighborhoods (p &lt;.01). Patients in Black neighborhoods (HR 1.24, 95% CI 1.16-1.33) had worse rwOS than patients in White (ref.) and Latinx neighborhoods (HR 0.90, 95% CI 0.83-0.97). Conclusions Our results suggest that racial/ethnic segregation is associated with inequities in breast cancer care and outcomes, where patients in predominantly Black and Latinx neighborhoods are less likely to receive timely care than those in White neighborhoods. Living in predominantly Black neighborhoods was also associated with reduced survival. Therefore, efforts to reduce cancer inequities should target higher-order structural factors associated with worse cancer care and outcomes, including segregation and other forms of structural racism.
Citation Format: Jenny S. Guadamuz, Gregory S. Calip, Alemseged A. Asfaw, Xiaoliang Wang, Harlan Pittell, Maneet Kaur, Amy E. Pierre, Cleo A. Ryals. Racial/Ethnic Segregation and Inequities in Metastatic Breast Cancer Treatment Initiation and Overall Survival [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD1-05.