Racial disparities in radium-223 treatment in a large real-world population.

Abstract

268 Background: Black men with prostate cancer are more likely to have unfavorable tumor characteristics and are at greater risk of prostate cancer mortality. Radium-223 is a FDA approved treatment for metastatic castration-resistant prostate cancer (mCRPC) that showed a survival benefit in the ALSYMPCA trial, where 94% of the participants were Caucasian. We aim to examine treatment patterns and outcomes of radium-223 in a large, heterogeneous population in the real world. Methods: We reviewed charts of all men with diagnosed with mCRPC in the entire Veterans Affairs (VA) system alive as of January 1st, 2013 who received radium-223. We compared common treatment patterns and characteristics between black and nonblack men. We analyzed predictors of time from radium-223 start to overall survival and time to skeletal related event (SRE) with Cox models. Results: 318 patients with bone mCRPC who received radium-223 were identified. 27% (87/318) were black. Black men were younger (67 vs 70 years, p = 0.001) and had higher PSA and alkaline phosphatase (ALP) levels at radium start (p = 0.014 and 0.017, respectively). There were no significant differences in biopsy Gleason, number of bone metastasis, primary localized treatment (yes/no), PSA doubling time, bone pain, or number of radium injections. Black men had lower mortality risk (HR 0.75; 95% CI 0.57 to 0.98; P = 0.038) on multivariable analysis. Comparison of common treatment patterns between black and nonblack men revealed that black men were more likely to receive other therapies prior to radium, including chemotherapy. Conclusions: Using a large, heterogeneous, real world cohort, we describe differences in treatment patterns and outcomes with radium-223 between black and nonblack men with mCRPC. While black men had a lower risk of mortality in this cohort, they had higher PSA and ALP levels when receiving radium-223. They were also more likely to receive other therapies prior to radium-223, indicating a possible delay in radium use in black men.