A pooled analysis including data from over 8,000 men showed survival outcomes were better for black men, after adjusting for prognostic variables.
In black men with metastatic castration-resistant prostate cancer who received chemotherapy as part of a clinical trial, overall survival (OS) was similar to OS of white men, according to the results of a pooled analysis (abstract LBA5005) presented at the 2018 Annual Meeting of the American Society of Clinical Oncology (ASCO), held June 1–5 in Chicago.
The analysis, which included data from more than 8,000 men, showed that black men had a 19% lower risk for death compared with white men, after adjusting for various prognostic factors.
“This was the largest analysis comparing survival outcomes in African-American men vs Caucasian men with advanced and lethal prostate cancer treated with docetaxel and prednisone,” said Susan Halabi, PhD, professor of biostatistics and bioinformatics at Duke University.
According to Halabi, despite the overall trends of declining incidence and mortality rates for prostate cancer, some studies have shown that black men have a higher incidence of the disease, and a higher mortality rate, than white men. However, many of these prior reports were limited by small sample size.
In the current study, the researchers hypothesized that black men with advanced prostate cancer would have worse survival than white men. They pooled data from nine phase III clinical trials with a primary endpoint of overall survival. The trials included 8,820 patients (6% of whom were black men). In the trials, patients were randomly assigned to docetaxel/prednisone or a docetaxel/prednisone-containing regimen.
The study showed that National Clinical Trials Networks (NCTN) studies enrolled a greater percentage of black men compared with industry trials (12% vs 4%). However, Halabi noted that NCTN studies were conducted in the United States, whereas industry-sponsored trials were conducted globally.
The median OS was similar between black patients and white patients (21.0 months vs 21.2 months).
Many black men in the studies had poor prognostic factors. For example, black men had higher prostate-specific antigen (PSA) levels and worse performance status. Because of that, the researchers performed a multivariable analysis of survival, adjusting for prognostic factors such as age, performance status, site of metastasis, PSA levels, alkaline phosphatase levels, and hemoglobin levels. The multivariable analysis showed a pooled hazard ratio for black patients compared with white patients of 0.81.
When the researchers restricted their analysis to the NCTN trials alone, median OS was similar between the two arms. However, in the multivariable adjusted analysis, the risk for death among black men was 24% lower than that for white men.
“These results are from phase III clinical trials and therefore cannot be generalized to the US population,” Halabi said. “New methodologies for enrolling higher proportions of African-American men should be actively pursued and vigorously implemented so minority groups are well represented on trials.”
Commenting on the results, ASCO Expert Robert Dreicer, MD, said he disagreed with Halabi’s emphasis that the findings cannot be generalized to the US population.
“This study adds to the growing body of evidence showing that black men with advanced prostate cancer who participate in clinical trials have the same, if not better, chance of survival as white men,” Dreicer said. “This research shows that by providing equal access to treatment, we can reduce racial disparities in outcomes for men with advanced prostate cancer.”