Individual Patient Data Analysis of Randomized Clinical Trials: Impact of Black Race on Castration-resistant Prostate Cancer Outcomes

Abstract

Background: Population data suggest that black men have a higher risk of dying from prostate cancer (PCa) than other racial ethnicities.

Objective: To examine the impact of black race on progression-free survival (PFS) and overall survival (OS) among men with metastatic castration-resistant PCa (mCRPC) enrolled in randomized controlled trials (RCTs).

Design, setting, and participants: A pooled analysis was performed on individual patient data from five modern PCa RCTs available from Project Data Sphere.

Outcome measurements and statistical analysis: Adjusted hazard ratios (HRs) were calculated to compare black and white race regarding PFS and OS. Subgroup analyses of mCRPC trials were performed based on the control arm treatments (mitoxantrone or docetaxel). Relevant covariates were used for adjustment in all analyses.

Results and limitations: A total of 1613 patients were included; 77 were black (4.7%). No significant differences between black and white men's baseline characteristics were noted regarding age, performance status, or pretreatment prostate-specific antigen. The pooled HRs for black race for OS and PFS were 1.01 (95% confidence interval [CI], 0.73-1.35) and 1.29 (95% CI, 0.95-1.76), respectively. The median OS for black compared with white men was 254 versus 238 d (p=0.92), respectively, with mitoxantrone and 581 versus 546 d (p=0.53), respectively, with docetaxel. The primary limitation was the relatively small number of black men enrolled in mCRPC clinical trials.

Conclusions: In the context of RCTs, in which patients receive generally uniform treatment, a significant difference in OS for black men could not be detected in mCRPC. Black men continue to be dramatically underrepresented in RCTs, and efforts are needed to increase minority accrual to these trials.

Patient summary: We looked at the outcomes of men treated in randomized controlled trials to determine the impact of black race on survival. We found that in the context of modern clinical trials, there does not appear to be a significant difference in survival between black and white races; however, a trend for greater progression in black men was noted.

Keywords: Disparity; Prostate cancer; Randomized controlled trial.