Despite presenting with high-risk disease, Black patients with prostate cancer who enrolled on radiation therapy clinical trials were reported to have better rates of biochemical recurrence, distant metastases, and prostate cancer–specific mortality than White patients.
Although Black patients with prostate cancer who enrolled on radiation therapy clinical trials had more aggressive disease, they had better rates of biochemical recurrence, distant metastases, and prostate cancer–specific mortality vs White patients, suggesting that other factors such as access to care may be important in achieving equity, according to findings from a meta-analysis published in JAMA Network Open.1
Findings from the trial, which had a median follow up of 10.6 months, indicated that Black patients, although more likely to have high-risk disease features, were less likely to experience biochemical recurrence (sHR, 0.88; 95% CI, 0.58-0.91), distant metastases (sHR, 0.72; 95% CI, 0.58-0.91), or prostate cancer–specific mortality (sHR, 0.72; 95% CI, 0.54-0.97). Moreover, no significant differences in all-cause mortality were observed (HR, 0.99; 95% CI, 0.92-1.07). Even after adjusting, investigators reported that Black race continued to be significantly associated with improvements in biochemical recurrence (adjusted sHR, 0.79; 95% CI, 0.72-0.88; P <.001), distant metastases (adjust sHR, 0.69; 95% CI, 0.55-0.87; P = .002), and prostate cancer–specific mortality (adjusted sHR, 0.68; 95% CI, 0.50-0.93; P = .01).
“These results do not suggest that there are no biological differences that might be associated with differences in prostate cancer incidence between racial groups,” the study authors wrote. “It is possible that the association with differential treatment response might be, at least in part, explained by differences in underlying biologic factors. Studies have reported distinct characteristics of prostate cancer in Black and White men at the genetic, epigenetic, and immunological level. These differences may have contributed to improved efficacy of multiple lines of systemic therapy in Black men compared with non-Black men with locally advanced or metastatic disease.”
Investigators conducted a literature search in order to identify relevant, randomized studies that were conducted via NRG Oncology or Radiation Therapy Oncology Group from January 1, 1990, to December 31, 2010; this was significant as both groups have historically included a significant population of Black patients within its clinical research. The trial's primary end points were biochemical recurrence, distant metastases, and prostate cancer–specific mortality, with the key secondary end point being all-cause mortality.
Investigators included a total of 8814 patients, 18.5% of whom were Black and 81.5% of whom were White. The mean patient age was 69.1 years in the overall study cohort and most patients were considered to be low- (19.8%) and intermediate-risk (48.4%) with a smaller group of high-risk patients (31.8%).
Investigators observed that Black patients presented at a significantly lower median age compared with White patients (68 years vs 71 years). Additionally, the population was more likely to present with high-risk prostate cancer (38.2% vs 30.4%; P <.001), higher prostate-specific antigen levels (10.3 vs 8.4; P <.001), and Gleason scores ranging between 8 and 10 (16.3% vs 14.1%; P = .03) vs White patients.
The 10-year cumulative incidences of biochemical recurrence, distant metastases, and prostate–cancer specific mortality in White and Black patients, respectively were 40.5% and 44.6% (P = .006), 8.4% and 11.6% (P = .005), and 4.5% and 6.4% (P = .03). The 10-year rate of all-cause mortality was comparable between White and Black patients (37.2% vs 36.6%; P = .50). Investigators clarified that prostate cancer–specific mortality rather than other cause mortality was responsible for the low rate of mortality events overall (6.5% vs 10.2%), in patients who were under 65 years of age (7.6% vs 14.9%), and older than 65 years (6.0% vs 9.2%). The same could be applied to patients with high-risk disease (6.4% vs 12.7%).
“These results provide high-level evidence challenging the common belief that Black men who are diagnosed with prostate cancer will necessarily have a worse prognosis than White men,” co-senior author Amar Kishan, MD, an associate professor and vice chair of clinical and translational research in the Department of Radiation Oncology at the University of California Los Angeles (UCLA) and a researcher at the UCLA Jonsson Comprehensive Cancer Center, said in a press release.2 “This is especially important because an unfounded belief can inadvertently contribute to ‘cancer injustice,’ leading to the use of more aggressive treatments than might be necessary—potentially reducing quality of life—and diverting attention away from other important factors that can influence outcome, including access to more comprehensive healthcare.”