LAUSR

OBJECTIVE Several recent studies on metastatic castration-resistant prostate cancer (mCRPC) demonstrated an improved overall survival for black vs. white men. Radium-223 is FDA approved for mCRPC based upon a survival benefit in the ALSYMPCA trial, where 94% of participants were white. We identified a real-world population of mCRPC patients who received radium-223 to compare differences in baseline characteristics and outcomes between black and non-black men. PATIENTS AND METHODS We reviewed charts of all men who received radium-223 in the entire Veterans Affairs system. We compared treatment patterns and baseline characteristics between black and non-black men. We used Cox models to analyze predictors of time from radium-223 start to overall survival and time to skeletal related events. RESULTS A total of 318 patients treated with radium-223 were identified. There were 87 (27%) black patients. Median follow-up after radium-223 initiation was 25.3 months (IQR 13.8-37.1 months). Black men were younger compared to non-black men when starting radium-223 (median 67 vs 70 years, p<0.001) and had higher PSA (median 159.9 vs 90.2 ng/mL, p=0.014) and alkaline phosphatase (ALP) (median 163 vs 135 IU/L, p=0.017). A greater proportion of black men received docetaxel prior to radium-223 (77% vs. 55%, p<0.001). On multivariable analysis, black race was associated with a decreased risk of mortality from time of radium-223 initiation (HR 0.75, 95% CI 0.57-0.99, p=0.045). CONCLUSIONS Black men had longer overall survival vs. non-black men despite appearing to receive radium later in their disease course. Further studies are required to verify our findings and explore biologic differences between black and non-black men with mCRPC.