Better outcomes with radiotherapy for Black versus White prostate cancer patients
medwireNews: Black men with localized prostate cancer fare better than their White counterparts after definitive radiotherapy, suggests a meta-analysis.
“Black men enrolled in randomized clinical trials presented with more aggressive disease features but had better treatment and disease-specific outcomes with [radiation]-based therapy compared with White men, suggesting other important factors associated with outcome, such as access to care, as sources of disparity,” write the researchers in JAMA Network Open.
Commentators Bogdana Schmidt and Neeraj Agarwal, both from University of Utah in Salt Lake City, USA, say that although the investigators “cannot stipulate that radiotherapy carries specific advantages for Black men with prostate cancer, they are able to suggest that, when under clinical trial care and receiving definitive therapy for localized disease, Black men have acceptable clinical outcomes.”
They continue: “Through a multidisciplinary effort of enriching cohort studies with Black men, enrolling Black men into clinical trials and continuing the search for tumor-specific genomic factors, treatment-specific response factors, and pharmacologic response differences, as a community we can unequivocally improve prostate cancer care for Black men.”
For the meta-analysis, the researchers collated individual patient data on 8814 participants of seven NRG Oncology/Radiation Therapy Oncology Group trials that evaluated definitive radiotherapy with or without short- or long-term androgen deprivation therapy. A total of 18.5% of the participants were Black and the remaining 81.5% were White.
The median age at enrolment was significantly lower for Black than White men (68 vs 71 years) and the median prostate-specific antigen (PSA) level was significantly higher (10.3 vs 8.4 ng/mL), as was the proportion presenting with high-risk disease (38.2 vs 30.4%) and Gleason scores of 8–10 (16.3 vs 14.1%).
Despite the presence of these high-risk features, the unadjusted cumulative rates at 10 years of biochemical recurrence, distant metastasis, and prostate cancer-specific mortality (PCSM) were significantly lower in Black than White participants, at 40.5% versus 44.6%, 8.4% versus 11.6%, and 4.5% versus 6.4%, respectively.
There was no significant between-group difference, however, in the 10-year incidence of all-cause mortality or a composite endpoint of death or distant metastasis.
The team then conducted a network meta-analysis and found that Black race was significantly associated with a reduced risk for biochemical recurrence, distant metastasis, and PCSM, with subdistribution hazard ratios of 0.79, 0.69, and 0.68, respectively, after accounting for age, initial PSA level, T category, Gleason score, and treatment strategy.
“These results provide high-level evidence to question the belief that prostate cancer among Black men necessarily portends a worse prognosis compared with White men,” say Amar Kishan, from the University of California, Los Angeles in the USA, and colleagues.
They add: “However, these results do not suggest that there are no biological differences that might be associated with differences in prostate cancer incidence between racial groups. It is possible that the association with differential treatment response might be, at least in part, explained by differences in underlying biologic factors.”
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