Treatment and survival of de novo metastatic hormone sensitive prostate cancer among African American US Veterans

5079 Background: Combinations of androgen deprivation therapy (ADT) plus docetaxel (DOC) or androgen signaling inhibitors (ASIs: abiraterone, enzalutamide, etc.) have revolutionized treatment of metastatic hormone sensitive prostate cancer (mHSPC), particularly for high volume disease. However, little is known about the use of and outcomes of combination therapy in African Americans (AA) with de novo mHSPC, due to their lack of representation in clinical studies. This study evaluates the patient characteristics, treatment, and survival in a cohort of US veterans with mHSPC with equal access to treatment under the Veterans Affairs Health System (VA). Methods: Veterans with mHSPC were identified from 2014-2022 in the VA using the initial pathological diagnosis of prostate cancer with SEER stage ‘distant’ and first ADT initiated within 1 month prior and 3 months after diagnosis. Therapies including DOC or ASIs were collected if initiated from 1 month prior to 4 months after ADT. Additional information at the time of diagnosis was collected including Prostate Specific Antigen (PSA), race from VA enrollment, and Charlson Comorbidity Index (CCI). Median survival was obtained for each group and stratified by PSA level >100 ng/mL. Chi-square and ANOVA testing were used differences in survival (OS) were assessed by log-rank testing. Results: 4,248 veterans with de novo mHSPC were identified, 1138 (26.8%) were AA and 3110 (73.2%) white. Black veterans were younger (70.8 vs. 74.8, p<0.001) and had higher median PSA (183 vs. 86.3, p<0.001) with similar mean CCI (4.4 vs. 4.4, p=0.78). AA veterans were likely to have a PSA >100 ng/mL at diagnosis (61.6% vs. 46.1%, p<0.001) and to receive combination therapy than white veterans (36.8% vs. 32.7%, p=0.01). The median OS among AA and white veterans was similar (32.5 months vs. 32.1, p=0.75). In 2,120 veterans with PSA>100 ng/mL (a surrogate for higher volume disease), AA veterans were more likely to receive combination therapy (39.5% vs. 32.9%, p=0.003) without differences in survival in AA veterans compared to white (31.0 vs. 26.9 months, p=0.18). Conclusions: In an equal access health care system, AA veterans had similar survival to white veterans despite having double the PSA levels, reflecting higher risk disease. AA presented 4 years younger and are likely treated with doublet therapy. The differences in the age of onset and burden of disease highlight persistent differences in populations with mHSPC. Further investigations to understand environmental, social, and tumor factors are warranted to explain these disparities. [Table: see text]