Abstract A049: Racial/ethnic and socioeconomic inequities in clinical trial participation among US community oncology patients, 2011-2021
Authors: Guadamuz Jenny , Mamtani Ronac , Wang Xiaoliang , Ryals Cleo A. , Altomare Ivy , Asfaw Alemseged A. , Castillo Wendy Camelo , Pittell Harlan , Calip Gregory S. , Sarkar Somnath 
Published: January 2023

Introduction: While oncology clinical trials disproportionately recruit from academic medical centers, most patients receive care in the community setting. However, there is limited information regarding clinical trial participation rates, including inequities by race/ethnicity and the social determinants of health (SDoH), in community practices. Here we assessed factors associated with clinical study drug (CSD, proxy for trial participation) receipt among patients diagnosed with 21 common cancers in community practices. Methods: This retrospective study used the nationwide Flatiron Health electronic health record-derived de-identified database of patients with cancer. The cohort included patients (≥ 18 years) diagnosed with cancer (initial, advanced, or metastatic diagnosis; depending on the cancer type) between January 2011 and November 2021 (follow-up through March 2022). We examined inequities in receipt of CSD after diagnosis by race/ethnicity, insurance coverage, and area-level SDoH indicators (e.g., socioeconomic status [SES] and predominant race/ethnicity [proxy for residential segregation]). SDoH indicators contextualizing where patients live were defined using Census block group/tract data from the American Community Survey (2015-2019). To evaluate factors associated with CSD receipt, we used time-to-event analysis where patients were followed from index diagnosis to their first documented receipt of CSD, death, or last recorded activity. Separate Cox proportional hazards models adjusted for clinical characteristics (i.e., age, sex, performance status, and stage) were used to calculate hazard ratios (HR) and 95% confidence intervals (CI). Results: This study included 196,270 patients (median age: 69 years, 49.5% women; 75.2% non-Hispanic/Latinx [NH] White, 6.2% NH-Black, 3.3% Latinx), of whom 3.7% received CSDs. Black (2.6%, HR 0.56 [CI: 0.51- 0.62]) and Latinx patients (2.6% (HR 0.54 [CI: 0.48-0.62]) were less likely to receive CSDs than white patients (4.3%). Individual and area-level SDoH were associated with CSD receipt. For example, patients without documented insurance (2.7%, HR 0.61 [CI: 0.56-0.66]) or with Medicaid coverage (2.6%, HR 0.58 [CI: 0.52-0.65]) were less likely to receive CSDs than patients with commercial coverage (4.7%). Patients living in predominately non-white and lower SES neighborhoods were less likely to receive CSDs, as were those in neighborhoods whose residents disproportionately lacked U.S. citizenship, had limited English proficiency, and had low rates of vehicle ownership. Conclusion: There are substantial inequities in CSD receipt among patients who receive care in community cancer clinics. Black, Latinx, and uninsured patients, as well as those from historically marginalized neighborhoods were less likely to receive CSDs. Without focused policy and operational efforts to increase clinical trial enrollment of racially, ethnically, and socio-demographically diverse patient populations, clinical trials may proliferate inequities in investigational drug access and potentially cancer outcomes.

Citation Format: Jenny Guadamuz, Ronac Mamtani, Xiaoliang Wang, Cleo A. Ryals, Ivy Altomare, Alemseged A. Asfaw, Wendy Camelo Castillo, Harlan Pittell, Gregory S. Calip, Somnath Sarkar. Racial/ethnic and socioeconomic inequities in clinical trial participation among US community oncology patients, 2011-2021 [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr A049.