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With equal access to care, prostate cancer outcomes similar among black, white men
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After controlling for nonbiological variations such as access to care and standardized treatment, black men with nonmetastatic prostate cancer had similar stage-for-stage cancer-specific mortality as white men, according to study results published in JAMA Oncology.
“Population-based estimates demonstrate that black men are more likely to be diagnosed with prostate cancer, more likely to present with distant metastases, and nearly 2.5 times more likely to die of the disease when compared with non-Hispanic white men,” Robert Dess, MD, assistant professor in the radiology department of Brighton Center for Specialty Care in Brighton, Michigan, and colleagues wrote. “Each year, the SEER database reports age-adjusted, prostate cancer-specific mortality rates. However, fulling adjusting for measurable and unmeasurable confounders within these registries is difficult.”
In the multiple-cohort study, Dess and colleagues sought to determine whether black race correlated with worse prostate cancer outcomes after adjusting for known prognostic variables and access to care.
The researchers used updated, individual patient-level data from 1992 to 2013 from men with clinical stage T1 to T4 N0-1M0 prostate cancer from the SEER cohort (n = 296,273), five equal-access regional medical centers within the VA health system (n = 3,972) and four combined NCI-sponsored Radiation Therapy Oncology Group phase 3 randomized clinical trials (n = 5,854).
The study population consisted of 306,100 men (mean age, 64.9 years; standard deviation, 8.9 years). Black men comprised 17.8% (n = 52,840) of the SEER cohort, 38.1% (n = 1,513) of the VA cohort and 19.3% (n = 1,129) of the randomized clinical trials (RCTs) cohort.
Patients in the VA cohort underwent curative surgery, whereas those in the RCT group received curative radiotherapy. Patients in the SEER cohort received radical therapy, hormone therapy or conservative management.
Cumulative prostate cancer-specific mortality served as the study’s primary outcome. Other-cause mortality served as a secondary outcome. The researchers employed stepwise inverse probability weighting (age-adjusted, age- and stage-adjusted, and fully adjusted) to control for demographic-, cancer-, and treatment-associated baseline differences.
Median follow-up was 75 months (interquartile range [IQR], 49-104) for the SEER cohort, 97 months (IQR, 59-144) for the VA cohort and 104 months (IQR, 68-132) for the RCT cohort.
Results showed that within the SEER cohort, black men had a 30% higher age-adjusted prostate cancer-specific mortality hazard (subdistribution HR [sHR] = 1.3; 95% CI, 1.23-1.37).
However, after full inverse probability weighting adjustment, black race appeared associated with an increase of only 0.5% (95% CI, 0.2-0.9) in prostate cancer-specific mortality at 10 years after diagnosis (sHR = 1.09; 95% CI, 1.04; 1.15). Researchers observed no significant difference for high-risk men (sHR = 1.04; 95% CI, 0.97-1.12).
Within the VA inverse probability-weighted cohort, there were no significant disparities in prostate cancer-specific mortality (sHR = 0.85; 95% CI, 0.56-1.3).
In the RCT inverse probability-weighted cohort, black men showed a significantly lower hazard (sHR = 0.81; 95% CI, 0.66-0.99).
Black men demonstrated significantly increased hazard of other-cause mortality in the inverse-probability weighted cohorts for SEER (sHR =1.3; 95% CI, 1.27-1.34) and RCT (sHR = 1.17; 1.06-1.29).
These results show that the anticancer effort “cannot be waged in a vacuum,” according to a related editorial by Channing J. Paller, MD, of Johns Hopkins University School of Medicine, Lin Wang, MSc, MMed, of Johns Hopkins Bloomberg School of Public Health, and Otis W. Brawley, MD, FACP, of Johns Hopkins University School of Medicine and a HemOnc Today Editorial Board Member.
“By controlling for access to care and quality of care through clinical settings where prostate cancer is treated, Dess and colleagues provide powerful evidence that equal treatment yields equal outcome among equal patients,” the editorial authors wrote. “It is an unsettling fact that there is not equal treatment in the United States. African Americans, other minorities and the poor in general often experienced disparate quality of care or no care at all. Although race does not matter biologically, race still matters.” – by Jennifer Byrne
Disclosures: Dess reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures. Brawley reports grants from the NCI and Bloomberg Philanthropies during the conduct of the study. Paller and Wang report no relevant disclosures.
Perspective
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David Y.T. Chen, MD, FACS
Dess and colleagues investigated the commonly held beliefs that black race is a risk factor for more aggressive prostate cancer, and that black men with prostate cancer experience worse outcomes overall compared with nonblack men. This has been recognized in general clinical experience and observational studies, but it has been unclear whether the difference for black men is due to biological factors, such as genetics, or nonbiological factors, such as unequal access to care and standardized treatment.The study examined over 55,400 black men, including those who were diagnosed with and treated for nonmetastatic prostate cancer within the SEER program — a U.S. population-based cohort registry — those cared for within equal-access VA hospitals and participants of four Radiation Therapy Oncology Group randomized clinical trials. Importantly, statistical analysis was applied to adjust for and balance socioeconomic and treatment variables.
The key findings are that outcomes between black and nonblack men were equivalent when equal access and standardized treatment were applied. This suggests that the difference in outcomes for black men with prostate cancer is not due to biological risk but rather barriers to access of high-quality medical care, from significant socioeconomic disparities that are systemic and present at the population level. This research emphasizes the importance of continued focus on addressing and correcting the modifiable nonbiological risk factors at the root of this racial health disparity.
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Dess RT, et al. JAMA Oncol. 2019;doi:10.1001/jamaoncol.2019.0826.
Paller CJ, Wang, L and Brawley, OW. JAMA Oncol. 2019;doi:10.1001/jamaoncol.2019.0812.
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