Abstract A075: Racial and ethnic inequities in receipt of degarelix among patients diagnosed with advanced prostate cancer in United States

Abstract Background: Prostate cancer (CaP) is the most commonly diagnosed non-cutaneous cancer among men in the United States (US). Limited data currently exists regarding inequities in access to androgen deprivation therapy (ADT) which is the backbone of systemic treatment in management of advanced CaP. Gonadotropin-releasing hormone (GnRH) antagonists, first approved in 2008, represent a novel class of ADT drugs with faster onset of action and without initial testosterone surge or symptom flare when compared to GnRH agonists. There is also some evidence that GnRH antagonists, compared to GnRH agonists, may be associated with lower cardiovascular complications. Thus, in this study, we assessed inequities in access to GnRH antagonist (degarelix) by examining the associations of race and ethnicity with initiation of this drug among patients diagnosed with distant CaP. Methods: Using the Surveillance, Epidemiology and End Results (SEER) data linked to Medicare fee-for-service (Parts A, B, and D), we identified a cohort of patients, at least 66 years of age, who were diagnosed with distant CaP between 2008 and 2019 with follow-up through 2020. We defined treatment initiation with a GnRH antagonist (degarelix) or GnRH agonists (leuprolide, goserelin, histrelin, or triptorelin) as starting treatment with the study drug within one year after diagnosis. Poisson regression models were used to estimate adjusted rate ratios (aRR) and 95% confidence intervals (CI) for the association between race and ethnicity and degarelix treatment initiation (vs GnRH agonists, no treatment). All models were adjusted for age and Gleason score and compared Non-Hispanic Black (NHB), Hispanic, Non-Hispanic Asian American and Pacific Islander (NHAAPI), and Non-Hispanic American Indian and Alaska Native (NHAIAN) with Non-Hispanic White (NHW) patients. Results: There were 25,277 patients diagnosed with CaP in our analytic cohort, 3,033 (12.0%) initiated degarelix, and 14,045 (55.6%) initiated GnRH agonists over the study period. Mean (SD) age in the study population was 77.8 (7.8). Among all patients, 19,231 (76.1%) were NHW, 3,013 (11.9%) were NHB, 2,075 (8.2%) were Hispanic, 770 (3.0%) were NHAAPI, and 119 (0.5%) were NHAIAN. In the primary analysis, NHB (aRR: 0.58, 95% CI: 0.51-0.66), Hispanic (aRR: 0.59, 95% CI: 0.51-0.69), NHAIAN (aRR: 0.85, 95% CI: 0.49-1.47), and NHAAPI (aRR: 0.75, 95% CI: 0.59-0.94) were less likely to initiate degarelix compared with NHW patients. Discussion: In this US population-based study of patients diagnosed with distant CaP, we observed lower rates of treatment initiation with degarelix among patients of all other racial and ethnic groups compared to NHW patients, which may suggest lower access to these new class of ADT in these groups. Additional research is needed to elucidate health systems, provider, and patient access barriers that contribute to these inequities. Citation Format: Farzin Khosrow-Khavar, Mingchao He, Elizabeth Handorf, Tina Mayer, Thomas Jang, Saum Ghodoussipour, David Golombos, Biren Saraiya, Elisa V. Bandera, Hari S. Iyer. Racial and ethnic inequities in receipt of degarelix among patients diagnosed with advanced prostate cancer in United States [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A075.