Access to Clinical Trials Reverses the Racial Disparity in Lethal Prostate Cancer

“We must learn to live together as brothers or we will all perish together as fools.” ― Martin Luther King Jr.

Most recent data from SEER reveal that black men in the US have 1.5 times greater chance of developing prostate cancer than white men, and are 2.2 times more likely to die from the disease1
If we consider for a moment that roughly 14% of the US population self identifies as black, and multiply this percent by 2.2, then as much as 31% of all prostate cancer deaths in the US are in black men. This may represent one of the greatest racial disparities in cancer in the US.  When compared to other racial groups such as Asian Americans, it is even greater.  Therefore, if we want to improve survival outcomes for prostate cancer in American men, we have to do so in black men.

Multiple factors contribute to this racial health disparity including social, cultural, educational and economic determinants, which limit access to and trust in healthcare. There are likely biologic factors as well that may account for more aggressive disease by race.  What is not clear is how black men respond to therapy compared to other racial groups.  One of the more provocative findings recently published in last month’s Journal of Clinical Oncology independently confirmed a previously described finding that black men with castration-resistant prostate cancer who participate in clinical trials may have better survival2.

The study, led by my colleague at Duke, Dr. Susan Halabi, was a large meta-analysis, involving 8,820 patients from 9 recently reported Phase III clinical trials, all involving docetaxel chemotherapy.  Combined, there were 500 self-identified black patients (from the US and abroad) accounting for 6% of all participants. There were 3 NCI-sponsored US studies, which enrolled 12% black men; the other 6 Industry-sponsored trials accrued only 4%, black men.  Overall, black men in these studies were younger, but also had a higher median PSA, lower hemoglobin and higher testosterone levels compared to white men, suggesting a worse overall prognosis. But, when adjusted for prognostic factors, black men survived 20% longer overall than white men (HR 0.81; 95% CI, 0.72 to 0.91; p <0.001).

The authors, of whom I am included, posed several explanations for these findings including possible selection bias, likely biologic differences in prostate cancers between black and white men, yet, unlikely differences in the metabolism and clearance of docetaxel chemotherapy, or unknown factors. But whatever the reasons, the reality is that the disparity outcome is closed, and maybe even reversed, when patients participate in clinical trials.  We concluded that “focused efforts to enhance clinical trial enrollment of black men should be pursued.” But how do we do that exactly, in an environment with ever-increasing restrictions, oversight, and cost associated with these trials?

Due to persistent real life impediments, access to clinical research seems to be shifting away from the patients who might benefit the most.  Perhaps a regulatory mandate to accrue minority patients into registration or post-marketing studies is needed?  I don’t know if that is the answer, but I do know that the status quo is not working. If we do not radically change how we engage and involve black men in our clinical trials then we will never fully understand this disease. 

References:
  1. “Surveillance, Epidemiology, and End Results Program.” Acute Myeloid Leukemia - Cancer Stat Facts, seer.cancer.gov/index.html.
  2. Halabi S, et al. Overall Survival of Black and White Men With Metastatic Castration-Resistant Prostate Cancer Treated With Docetaxel. J Clin Oncol. 2018 Dec 21:JCO1801279. [Epub ahead of print]
Written by: Daniel J. George, MD, Medical Oncologist, Professor of Medicine, Professor of Surgery, Duke Cancer Institute, Durham, North Carolina


Further Related Content:
Watch: Survival Outcomes in Metastatic Castration-Resistant Prostate Cancer (mCRPC) for Black versus White Men-Susan Halabi
Watch: Clinical Implications of the Abi Race Study: Interview with Dan George
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