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Original Investigation
May 23, 2019

Association of Black Race With Prostate Cancer–Specific and Other-Cause Mortality

Author Affiliations
  • 1Department of Radiation Oncology, University of Michigan, Ann Arbor
  • 2Department of Biostatistics, University of Michigan, Ann Arbor
  • 3Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
  • 4Department of Radiation Oncology, Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Virginia
  • 5Department of Urology, University of California, San Francisco
  • 6Department of Urology, Oregon Health and Science University, Portland
  • 7Department of Urology, University of California, Los Angeles
  • 8Department of Urology, University of California, San Diego
  • 9Department of Urology, Augusta University, Augusta, Georgia
  • 10Department of Radiation Oncology, Cedars Sinai, West Hollywood, California
  • 11Department of Radiology, Weill Cornell, New York, New York
  • 12Department of Urology, University of Michigan, Ann Arbor
  • 13Department of Pathology, University of Michigan, Ann Arbor
  • 14Department of Radiation Oncology, University of California, Los Angeles
  • 15Department of Urology, Northwestern University, Chicago, Illinois
  • 16Department of Radiation Oncology, University of California, San Francisco
  • 17Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
  • 18Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
  • 19Department of Urology, Cedars-Sinai Medical Center, Los Angeles, California
  • 20Section of Urology, Durham VA Medical Center, Durham, North Carolina
  • 21Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina
  • 22Department of Biostatistics, University of Chicago, Chicago, Illinois
JAMA Oncol. Published online May 23, 2019. doi:10.1001/jamaoncol.2019.0826
Key Points

Question  Is black race associated with worse prostate cancer outcomes after controlling for known prognostic variables and access to care?

Findings  In this multiple-cohort study of 306 100 patients with prostate cancer, black race was not associated with inferior prostate cancer–specific mortality in cohorts from Veterans Affairs health system and National Cancer Institute–sponsored randomized clinical trials. Black race was associated with increased prostate cancer–specific mortality within the Surveillance, Epidemiology, and End Results US population registry, but not in the high-risk subgroup after baseline covariable adjustment, although black race remained associated with increased other-cause mortality.

Meaning  With similar access to care and standardized treatment, black men with nonmetastatic prostate cancer appeared to have comparable stage-for-stage prostate cancer–specific mortality to white men.

Abstract

Importance  Black men are more likely to die of prostate cancer than white men. In men with similar stages of disease, the contribution of biological vs nonbiological differences to this observed disparity is unclear.

Objective  To quantify the association of black race with long-term survival outcomes after controlling for known prognostic variables and access to care among men with prostate cancer.

Design, Setting, and Participants  This multiple-cohort study included updated individual patient-level data of men with clinical T1-4N0-1M0 prostate cancer from the following 3 cohorts: Surveillance, Epidemiology, and End Results (SEER [n = 296 273]); 5 equal-access regional medical centers within the Veterans Affairs health system (VA [n = 3972]); and 4 pooled National Cancer Institute–sponsored Radiation Therapy Oncology Group phase 3 randomized clinical trials (RCTs [n = 5854]). Data were collected in the 3 cohorts from January 1, 1992, through December 31, 2013, and analyzed from April 27, 2017, through April 13, 2019.

Exposures  In the VA and RCT cohorts, all patients received surgery and radiotherapy, respectively, with curative intent. In SEER, radical treatment, hormone therapy, or conservative management were received.

Main Outcomes and Measures  Prostate cancer–specific mortality (PCSM). Secondary measures included other-cause mortality (OCM). To adjust for demographic-, cancer-, and treatment-related baseline differences, inverse probability weighting (IPW) was performed.

Results  Among the 306 100 participants included in the analysis (mean [SD] age, 64.9 [8.9] years), black men constituted 52 840 patients (17.8%) in the SEER cohort, 1513 (38.1%) in the VA cohort, and 1129 (19.3%) in the RCT cohort. Black race was associated with an increased age-adjusted PCSM hazard (subdistribution hazard ratio [sHR], 1.30; 95% CI, 1.23-1.37; P < .001) within the SEER cohort. After IPW adjustment, black race was associated with a 0.5% (95% CI, 0.2%-0.9%) increase in PCSM at 10 years after diagnosis (sHR, 1.09; 95% CI, 1.04-1.15; P < .001), with no significant difference for high-risk men (sHR, 1.04; 95% CI, 0.97-1.12; P = .29). No significant differences in PCSM were found in the VA IPW cohort (sHR, 0.85; 95% CI, 0.56-1.30; P = .46), and black men had a significantly lower hazard in the RCT IPW cohort (sHR, 0.81; 95% CI, 0.66-0.99; P = .04). Black men had a significantly increased hazard of OCM in the SEER (sHR, 1.30; 95% CI, 1.27-1.34; P < .001) and RCT (sHR, 1.17; 95% CI, 1.06-1.29; P = .002) IPW cohorts.

Conclusions and Relevance  In this study, after adjustment for nonbiological differences, notably access to care and standardized treatment, black race did not appear to be associated with inferior stage-for-stage PCSM. A large disparity remained in OCM for black men with nonmetastatic prostate cancer.

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