Overall Survival of Black and White Men With Metastatic Castration-Resistant Prostate Cancer Treated With Docetaxel

Abstract

Purpose: Several studies have reported that among patients with localized prostate cancer, black men have a shorter overall survival (OS) time than white men, but few data exist for men with advanced prostate cancer. The primary goal of this analysis was to compare the OS in black and white men with metastatic castration-resistant prostate cancer (mCRPC) who were treated in phase III clinical trials with docetaxel plus prednisone (DP) or a DP-containing regimen.

Methods: Individual participant data from 8,820 men with mCRPC randomly assigned in nine phase III trials to DP or a DP-containing regimen were combined. Race was based on self-report. The primary end point was OS. The Cox proportional hazards regression model was used to assess the prognostic importance of race (black v white) adjusted for established risk factors common across the trials (age, prostate-specific antigen, performance status, alkaline phosphatase, hemoglobin, and sites of metastases).

Results: Of 8,820 men, 7,528 (85%) were white, 500 (6%) were black, 424 (5%) were Asian, and 368 (4%) were of unknown race. Black men were younger and had worse performance status, higher testosterone and prostate-specific antigen, and lower hemoglobin than white men. Despite these differences, the median OS was 21.0 months (95% CI, 19.4 to 22.5 months) versus 21.2 months (95% CI, 20.8 to 21.7 months) in black and white men, respectively. The pooled multivariable hazard ratio of 0.81 (95% CI, 0.72 to 0.91) demonstrates that overall, black men have a statistically significant decreased risk of death compared with white men ( P < .001).

Conclusion: When adjusted for known prognostic factors, we observed a statistically significant increased OS in black versus white men with mCRPC who were enrolled in these clinical trials. The mechanism for these differences is not known.

FIG 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses diagram of how the trials were identified and screened. DP, docetaxel and prednisone; mCRPC, metastatic castration-resistant prostate cancer; OS, overall survival.

FIG 2.

(A) Kaplan-Meier curves of overall survival (OS) by race and (B) forest plot with hazard ratios (HRs) comparing black men with white men (reference group, white men; Q = 10.738; df = 8; P = .217; I² = 0.255). CALGB, Cancer and Leukemia Group B; ENTHUSE 33 (ClinicalTrials.gov identifier: NCT00617669); MAINSAIL (ClinicalTrials.gov identifier: NCT00988208); NR, not reported; READY (ClinicalTrials.gov identifier: NCT00744497); SYNERGY (ClinicalTrials.gov identifier: NCT NCT01188187); SWOG, Southwest Oncology Group; SWOG 0421 (ClinicalTrials.gov identifier: NCT00134056); SWOG 9916 (ClinicalTrials.gov identifier: NCT00004001); SWOG 90401 (ClinicalTrials.gov identifier: NCT00110214); TAX 327 (Docetaxel Plus Prednisone or Mitoxantrone Plus Prednisone for Advanced Prostate Cancer; VENICE (ClinicalTrials.gov identifier: NCT00519285).

FIG 3.

(A) Kaplan-Meier curves of overall survival (OS) by race and (B) forest plot with hazard ratios (HRs) comparing black men with white men enrolled in the National Cancer Institute National Clinical Trials Network (reference group, white men; Q = 0.216; df = 2; P = .898; I² = 0.000).

FIG A1.

Frequency distribution of black and white men across trials. CALGB, Cancer and Leukemia Group B; CALGB 90401 (ClinicalTrials.gov identifier: NCT00110214); ENTHUSE 33 (ClinicalTrials.gov identifier: NCT00617669); MAINSAIL (ClinicalTrials.gov identifier: NCT00988208); READY (ClinicalTrials.gov identifier: NCT00744497); SWOG, Southwest Oncology Group; SWOG 9916 (ClinicalTrials.gov identifier: NCT00004001); SYNERGY (ClinicalTrials.gov identifier: NCT NCT01188187); TAX 327 (Docetaxel Plus Prednisone or Mitoxantrone Plus Prednisone for Advanced Prostate Cancer); VENICE (ClinicalTrials.gov identifier: NCT00519285).

FIG A2.

(A) Kaplan-Meier overall survival (OS) curves by race and (B) forest plot with hazard ratios (HRs) comparing black with white men randomly assigned to the DP arm only (reference group, white men; Q = 9.778; df = 8; P = .281; I² = 0.182). MAINSAIL (ClinicalTrials.gov identifier: NCT00988208); NR, not reported; READY (ClinicalTrials.gov identifier: NCT00744497); SYNERGY (ClinicalTrials.gov identifier: NCT NCT01188187); VENICE (ClinicalTrials.gov identifier: NCT00519285).

FIG A3.

(A) Kaplan-Meier overall survival (OS) curves by race and (B) forest plot with hazard ratios (HRs) comparing black men with white men in patients enrolled in the National Cancer Institute National Clinical Trials Network and docetaxel and prednisone arm only (reference group, white men; Q = 0.441; df = 2; P = .802; I² = 0.000). CALGB, Cancer and Leukemia Group B; CALGB 90401 (ClinicalTrials.gov identifier: NCT00110214); SWOG, Southwest Oncology Group; SWOG 0421 (ClinicalTrials.gov identifier: NCT00134056). SWOG 9916 (ClinicalTrials.gov identifier: NCT00004001).