Blacks in clinical trials respond better than whites to radiation for localized prostate cancer

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By Marilynn Larkin

NEW YORK (Reuters Health) - Among men with localized prostate cancer enrolled in clinical trials, Blacks had more aggressive disease but also better treatment outcomes than whites, a meta-analysis shows.

"We were surprised to see how robust the results were - improved outcomes across the board, even for early disease endpoints like biochemical recurrence," Dr. Amar Kishan of the University of California, Los Angeles told Reuters Health by email. "Prior lines of evidence had hinted at the differences favoring Black men in terms of prostate cancer-specific mortality and survival in advanced disease, but here we are looking at very early endpoints as well."

As reported in JAMA Network Open, Dr. Kishan and colleagues searched the literature for randomized controlled trials of Blacks and whites receiving radiation therapy for localized prostate cancer conducted by the NRG Oncology/Radiation Therapy Oncology Group from 1990 - 2010.

The main outcomes were subdistribution hazard ratios (sHRs) of biochemical recurrence (BCR), distant metastases (DM), and prostate cancer-specific mortality (PCSM).

Seven randomized clinical trials involving 8,814 patients (mean age, 69; 18.5% Black) were included; the median follow-up for survivors was 10.6 years.

At enrollment, Blacks were more likely to have high-risk disease features. However, even without adjustment, they were less likely to experience BCR (sHR, 0.88), DM (sHR, 0.72), or PCSM (sHR, 0.72).

After adjustment, Black race remained significantly associated with improved BCR (adjusted sHR, 0.79), DM (asHR, 0.69), and PCSM (asHR, 0.68).

No significant between-race differences were seen in all-cause mortality (HR, 0.99).

The authors note, "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. 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."

Dr. Kishan explained, "There are no data to suggest that prostate cancer is inherently more aggressive in Black men who are presenting for treatment. Standard of care should be abided by, and we should always be cognizant of any barriers to healthcare access that might hamper outcomes."

"The main message is actually that if timely diagnoses are made and impediments to healthcare are lifted, outcomes might be improved at large," he added. "It should not take enrollment on a clinical trial to receive a timely diagnosis or standard of care treatment."

Dr. Neeraj Agarwal of the University of Utah in Salt Lake City, coauthor of a related editorial, commented in an email to Reuters Health, "Although the epidemiologic data strongly suggest that Black men are significantly more likely to die of prostate cancer than white men, when enrolled on clinical trials, Black men experience at least as good an outcome as white men."

"Based on these observations," he said, "it is very likely that inferior outcomes in Black men at the population level are associated with inequitable access to healthcare rather than a more aggressive prostate cancer, as currently believed widely."

"The only way in my view to mitigate the difference in the outcomes between Black and White men with prostate cancer is to ensure equitable access to health care," Dr. Agarwal concluded.

SOURCES: https://bit.ly/3Hs9oFQ and https://bit.ly/3qSGLep JAMA Network Open, online December 29, 2021.

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