Bridging the Survival Gap: A Retrospective Study Comparing Docetaxel, Abiraterone, and Enzalutamide in Black and White Men with Metastatic Prostate Cancer in the Veterans Affairs System

Summary: It is well established that Black men who have localized prostate cancer have shorter overall survival (OS) times than White men. However, the same data comparing OS between races with advanced prostate cancer is limited. The primary goal of this analysis was to compare OS of Black and White men with metastatic disease (at the time of diagnosis) who are receiving either abiraterone, docetaxel, or enzalutamide as the first line of therapy. We conducted a retrospective cohort study of patients in the Veterans Health Administration (VHA) with metastatic prostate cancer treated with either abiraterone, docetaxel, or enzalutamide. Outcomes included overall survival (OS) and time to second-line therapy as assessed by Kaplan-Meier analysis. : In this retrospective cohort study, we identified 3,476 veterans with metastatic prostate cancer who had metastatic disease identified in bone, lymph nodes, or viscera. Median follow-up was 5 years. To compare overall survival, we used Kaplan-Meier curves to compare OS between Black and White men receiving abiraterone, enzalutamide, and docetaxel. Overall survival (OS) rates were higher among Black men receiving first-line docetaxel compared to first-line abiraterone or first-line enzalutamide. For those on docetaxel, 5-year OS for Black men was 11% compared to White men at 7%, Log Rank p=0.0356. There was no difference in time to second-line therapy in docetaxel by race. There was no difference in OS or time to second-line therapy by race for either abiraterone or enzalutamide. There was also no difference in OS outcomes by site of initial metastases (LN, bone, visceral) for docetaxel, abiraterone, or enzalutamide as first-line therapy. The highest baseline comorbidity scores were associated with initial enzalutamide use and the lowest baseline comorbidity scores were associated with initial docetaxel use, ANOVA p < 0.001. However, initial docetaxel was associated with a higher likelihood of initial visceral metastatic disease. We observed a statistically significant increase in OS in Black versus White men with metastatic prostate cancer who were given docetaxel as their first line of therapy when compared to abiraterone and enzalutamide. Our data suggest that docetaxel may be more effective as the first-line therapy for Black men with metastatic prostate cancer. Eliane C. Garlock (she/her/hers), DO (Presenting Author) - VCU Health; Raj Singh, MD (Co-Author) - Ohio State; Michael Chang (he/him/his), MD (Co-Author) - Hunter Holmes McGuire VA Medical Center; Hann-Hsiang Chao, MD/PhD (Co-Author) - Central Virginia VA Health Care System