Race Difference in Prostate Cancer Disappears With Equal Access

Kerry Dooley Young

May 24, 2019

Race was not associated with higher rates of dying from prostate cancer in an analysis that looked at how black and white men had fared when treated in settings where patients had standardized access to care.

The study was published online May 23 in JAMA Oncology.

Previous research found that black men were nearly 2.5 times more likely to die of prostate cancer when compared with non-Hispanic white men, note the authors, led by Robert T. Dess, MD, of the University of Michigan.

In their study, they set out to find how much of this difference could be attributed to access to care.

They contrasted results from a large federal registry, which they write reflects "multiple socioeconomic barriers to quality care" experienced by black men, to those from two settings where care was more standardized. These were the Veterans Affairs (VA) health system and the Radiation Therapy Oncology Group phase 3 randomized clinical trials (RCTs), sponsored by the National Cancer Institute (NCI).

For men who were treated within systems with equal access to care (VA cohort) or within the standardized treatment approach and follow-up of a cooperative group trial (RCT cohort), there was no difference in the prostate cancer specific mortality (PCSM) rates between black and white patients.

This finding adds to a growing body of evidence pointing to gaps in treatment, and not race itself, as a cause of higher mortality rates for black men from prostate cancer, the authors comment.

In an invited commentary, Channing J. Paller, MD; Lin Wang, MSc, MMed; and Otis W. Brawley, MD, all of Johns Hopkins University, write that the new research provided "powerful evidence that equal treatment yields equal outcome among equal patients."

"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 experience disparate quality of care or no care at all," the editorialists comment.

There could be genomic factors at play in the experience of black men with prostate cancer, which merit further research, they add. However, they emphasize a need to immediately improve the care of black patients.

"We as health care professionals are likely to have the greatest effect on improved outcomes for African American patients with prostate cancer by ensuring that they get the same care as white patients, not just in clinical trials but throughout the national health care system," the editorialists add.

Study Details

The study was designed to tease out the effects of access to care in outcomes. To represent the general population, the authors used the NCI's Surveillance, Epidemiology, and End Results (SEER) database, which reports age-adjusted PCSM rates.

SEER data was then compared to results from a multicenter cohort from five regional hospitals within the VA health system and a cohort treated in four NCI-sponsored Radiation Therapy Oncology Group RCTs.

Dess and co-authors write that inverse probability weighting (IPW) was done to adjust for demographic, cancer, and treatment-related baseline differences.

After fully adjusting IPW, they found within SEER that black race was associated with a 0.5% absolute increased rate of prostate cancer specific mortality at 10 years, with no statistically significant difference evident in the high-risk subgroup.

However, black race was not associated with inferior PCSM outcomes in men who had equal access to care (VA cohort) or were taking part in clinical trials (RCT cohort).

In fact, a deeper look at the results via subdistribution hazard ratios (sHR) indicates better outcomes for black men, with this association reaching statistical significance within the RCT cohort (sHR, 0.81; P = .04).

Dess and co-authors found that in the general population, as suggested by SEER, black men seemed more likely to face barriers to care, including lower rates of insurance and lower income.

"Black race remains associated with many factors that negatively affect outcomes, and disparities persist at the population level," the authors write. "Continued efforts are needed to address this clear racial health inequity driven by modifiable nonbiological risk factors."

In their commentary, Paller, Wang, and Brawley note that "race is a complex sociopolitical construct rather than a biological categorization." They cite as an example how the US Office of Management and Budget (OMB) defines race for demographic data before every decennial national census. As a result, some people have been moved from one race to another multiple times during the past five decades, they write.

Still, black race "generally correlates" with being more likely to struggle to get quality healthcare, the editorialists comment.

"The primary issue becomes not to develop therapies that are more appropriate for minorities, but rather to provide all people with the quality medical care (preventive, diagnostic, and therapeutic) that they need," they add.

Authors of the study reported financial ties unrelated to the paper with AbbVie, American College of Radiology/NRG Oncology, Astellas, Augmenix, Bayer, Blue Earth, Cota, Dendreon, EMD Serono, Ferring, GenomeDx, Integra Life Science Services, Janssen Pharmaceuticals, MDx Health, Medivation, Nanobiotix, OPKO Health, PFS Genomics, Sanofi, Scripps Proton Therapy Center, ViewRay, Varian Medical Systems, and Vivos. Editorialist Brawley reported receiving grants from the National Cancer Institute and Bloomberg Philanthropies during the conduct of the study.

JAMA Oncol. Published online May 23, 2019. Abstract, Editorial

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