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Black men may survive longer than white men after chemotherapy for advanced prostate cancer
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CHICAGO — Black men who undergo chemotherapy for advanced prostate cancer may achieve better outcomes than white men who receive the same treatment, according to study results presented at ASCO Annual Meeting.
An analysis of more than 8,000 men with chemotherapy-naive disease enrolled on phase 3 trials showed no difference in median OS between racial groups. However, when researchers adjusted for key factors that affect survival, results revealed a reduced risk for death among black men.
“By pooling data across clinical trials, this study provided a unique opportunity to evaluate how race might affect prostate cancer response to treatment,” Susan Halabi, PhD, FASCO, professor of biostatistics and bioinformatics at Duke University, said in a press release.
Prior studies suggested white men with metastatic castration-resistant prostate cancer survived longer than black men; however, those reports have been limited by small sample size, according to study background.
Halabi and colleagues analyzed individual patient data from 8,871 men with castration-resistant prostate cancer enrolled on one of nine phase 3 trials that included OS as a key endpoint.
All men received docetaxel/prednisone alone or a regimen that contained those agents.
Trial participants self-reported race (85% white, 6% black, 5% Asian and 4% unspecified).
Investigators used the proportional hazards model to determine the prognostic importance of white race vs. black race.
The final analysis included 8,542 men (median age, 69 years) who identified themselves as white or black and had performance status of 0 or 1. Median hemoglobin was 12.9 g/dL, median PSA was 86 ng/mL, and media alkaline phosphatase was 139 U/L.
The majority (72%) of men had bone metastases with or without lymph node involvement; 9% had lung metastases; 9% had liver metastases; and 7% had lymph node involvement only.
Results of an unadjusted analysis showed no statistically significant difference in median OS between black men (21 months, 95% CI, 19.4-22.5) and white men (21.2 months; 95% Ci, 20.8-21.7).
However, multivariable analysis that adjusted for established risk factors — including age, PSA, performance status, site of metastases, and alkaline phosphatase and hemoglobin level — revealed a statistically significant reduction in death among black men (HR = 0.81; 95% CI, 0.72-0.92).
Halabi reported an “even more striking” survival benefit among black men when researchers restricted their analysis to patients enrolled in NCI’s National Clinical Trials Network (HR = 0.76; P < .0001).
Because these results are from phase 3 clinical trials, they cannot be generalized to the U.S. population, Halabi said.
However, the lower risk for death among black men may reflect differences in disease biology or suggest that black men better tolerate the docetaxel-prednisone combination, Halabi said. Genomic analyses will evaluate whether biologic variations may explain the differences in outcomes by race.
The analysis also highlighted the low enrollment of black men in phase 3 trials.
Black individuals account for nearly 13% of the U.S. population, but only 6% of men enrolled on the analyzed trials identified themselves as black.
“This study underscores the importance of increasing the participation of racial minorities in clinical trials,” Halabi said. “New methodologies for enrolling higher numbers of African-American men should be actively pursued and vigorously implemented.” – by Mark Leiser
For more information:
Halabi S, et al. Abstract LBA5005. Presented at: ASCO Annual Meeting; June 1-5, 2018; Chicago.
Disclosures: The researchers report funding from Congressionally Directed Medical Research Programs. Halabi reports consultant or advisory roles with Bayer, Eisai and Tokai Pharmaceuticals, as well as travel, accommodations or expenses from Bayer. Please see the abstract for all other authors’ relevant financial disclosures.
Perspective
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Robert Dreicer, MD, MS, MACP, FASCO
Despite [the contention from Halabi and colleagues] that these findings cannot be generalized to the broader U.S. population, I would argue that what this study tells us is pretty striking. African-American men who receive conventional therapies have potentially better survival [than white men]. These were men who were enrolled on clinical trials, but this is a conventional therapy. I think access to care needs to be emphasized here. The nihilism associated with prostate cancer among African-American men is not supported by this really interesting work.
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David Michael Nanus, MD
The fact median OS was the same isn’t too surprising. I was a little surprised by the multivariate analysis, which showed African-Americans actually did better. I think it is helpful to be able to tell these patients they are likely to do as well, if not better, with chemotherapy.
I think we have this bias that African-American men or other underrepresented minorities do worse than Caucasians in many diseases, including prostate cancer. There is debate about whether this may be due to biological differences, access to care or other social factors we don’t always think about — for example, if they have access to care, do they continue on care?
This study helps dismiss at least some of these biases and really suggests that, if a patient gets the right care, they will do well. It reinforces the fact that every patient with advanced castrate-resistant prostate cancer should get every possible therapy regardless of race or background.
Because these are older studies and it’s a multidisciplinary analysis looking at large databases, we don’t know all of the details about every patient. We know nothing about molecular profiling or mutational profiling of these patients and what impact that may have on certain subsets.
The final line of the abstract is really what it’s all about: Understanding the biological variation by race among men with castrate-resistant prostate cancer is very important, and it will help us find the right therapy for the right patient.
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