Black men with localized prostate cancer had better treatment- and disease-specific outcomes than white men when treated with definitive radiotherapy, according to the results of a meta-analysis.

Even though Black men were more likely to present with high-risk features, they were less likely to experience biochemical recurrence (subdistribution hazard ratio [sHR] 0.88, 95% CI 0.80-0.96, P=0.006), distant metastases (sHR 0.72, 95% CI 0.58-0.91, P=0.005), and prostate cancer-specific mortality (sHR 0.72, 95% CI 0.54-0.97, P=0.03), reported Amar Kishan, MD, of the University of California Los Angeles, and colleagues.

After adjusting for age, initial prostate-specific antigen (PSA) level, T category, Gleason score, and treatment strategy, Black race remained significantly associated with improved biochemical recurrence (sHR 0.79, 95% CI 0.72-0.88, P<0.001), distant metastases (sHR 0.69, 95% CI 0.55-0.87, P=0.002), and prostate cancer-specific mortality (sHR 0.68, 95% CI 0.5-0.93, P=0.01), they noted in JAMA Network Open.

There were no significant differences, however, in time to all-cause mortality, time to other-cause mortality, and distant metastases or death between Black and white men.

These results were “novel and unexpected” and “provide high-level evidence to question the belief that prostate cancer among Black men necessarily portends a worse prognosis compared with white men,” Kishan and colleagues wrote. “This belief may be a factor in differences in the approach to cancer therapy, thereby leading to the use of more aggressive treatments than might be necessary, which carry greater risks of decreasing the quality of life and distracting attention from other important factors associated with outcome and sources of disparity, such as access to care.”

While Black men have a two-fold higher risk of dying from prostate cancer, Kishan and colleagues pointed out that race-specific differences in response to initial treatment remain unknown.

In an accompanying commentary, Bogdana Schmidt, MD, MPH, and Neeraj Agarwal, MD, both of the Huntsman Cancer Institute at the University of Utah in Salt Lake City, observed that clinical trial enrollment “may hold the key to these findings.”

“We have seen that Black men who receive state-of-the-art care through clinical trials or have access to high-volume centers do not experience the adverse outcomes we know Black men do on the population level,” they wrote.

Enrolling more Black men into clinical trials, as well as more research into “tumor-specific genomic factors, treatment-specific response factors, and pharmacologic response differences,” can “unequivocally improve prostate cancer care for Black men,” they added.

This meta-analysis included seven relevant randomized clinical trials from 1990 to 2010 that evaluated definitive radiotherapy with or without short- or long-term androgen deprivation therapy, conducted by the NRG Oncology/Radiation Therapy Oncology Group, which has historically enrolled a large number of Black men in its trials, the authors noted.

The primary outcomes of interest were biochemical recurrence, distant metastases, and prostate cancer-specific mortality.

A total of 8,814 patients (18.5% Black, mean age 69) were included in the analysis. Median follow-up for surviving patients was 10.6 years.

Kishan and colleagues found that Black patients were significantly more likely than white patients to present with:

• Younger age: median 68 vs 71 years (P<0.001)
• High-risk disease: 38.2% vs 30.4%, respectively (P<0.001)
• Higher PSA levels: median 10.3 vs 8.4 ng/mL (P<0.001)
• Higher Gleason scores of 8 to 10: 16.3% vs 14.1% (P=0.03)

In addition, Black men had lower absolute unadjusted 10-year cumulative incidence rates of biochemical recurrence (40.5% vs 44.6%, P=0.006), distant metastases (8.4% vs 11.6%, P=0.005), and prostate cancer-specific mortality (4.5% vs 6.4%, P=0.03) compared with white men.

The 10-year rate of all-cause mortality was similar between the groups.

Kishan and colleagues noted that none of the included trials were designed to investigate associations between race and outcome with the trial intervention. “Therefore, these comparisons are post hoc and susceptible to residual confounding beyond what would be expected for optimal prespecified subgroup analyses,” they wrote.