African-Americans fare well with chemo for PCa

Chicago-Median overall survival for African-American men with advanced prostate cancer who are treated with docetaxel (Taxotere) is similar to that of Caucasian men, according to an analysis of pooled data from nine randomized phase III clinical trials.

When adjusting for established risk factors, African-American men had a 19% lower risk for death than Caucasian men, Susan Halabi, PhD, reported at the American Society of Clinical Oncology annual meeting in Chicago.

“This is the largest analysis comparing survival outcomes in African-American men versus Caucasian men in men with advanced and lethal prostate cancer that are treated with docetaxel and prednisone,” said Dr. Halabi, professor of biostatistics and bioinformatics at Duke University in Durham, NC. “In the first analysis, looking at the aggregate data, the survival distribution in African-American and Caucasian men appears to be the same, with a median survival duration of 21 months.

“When we zoom in and perform another type of analysis that adjusts for important variables that will affect the outcome, to our surprise what we found is that the relative risk of death was 19% lower for African-American men than for Caucasian men, and this was statistically significant.”

Also see: Rethinking race and prostate cancer outcomes

Despite an overall trend toward a declining incidence of prostate cancer and its associated mortality, African-American men have a higher incidence and mortality rate than Caucasian men. In addition, they are diagnosed at a later stage of prostate cancer than are Caucasian men. Access to health care has been described as unequal. Based on this information, her study group sought to test the hypothesis that African-American men who are enrolled in clinical trials on docetaxel and prednisone and who have advanced and lethal prostate cancer (metastatic castration-resistant prostate cancer) have worse survival outcomes than Caucasian men.

They identified nine phase III clinical trials of men with advanced prostate cancer with overall survival (OS) as a primary outcome. These nine trials included 8,820 men, of whom 85% were Caucasian, 6% were African-American, 5% were Asian, and 4% were other/unknown.

The National Cancer Institute/National Clinical Trials Network enrolled a higher proportion of African-American men than industry-sponsored trials (12% vs. 4%).

“It is important to know that the National Cancer Institute/National Clinical Trials Network trials were conducted in the U.S., whereas industry-sponsored trials were conducted globally,” said Dr. Halabi.

Next: Hazard ratio for OS in African-American men versus Caucasian men was 0.81After adjustment for age, performance status, PSA level, site of metastases, and levels of hemoglobin and alkaline phosphatase, the hazard ratio (HR) for OS in African-American men versus Caucasian men was 0.81 (p=.004).

“When we restrict our analysis to the three trials that were conducted by the National Clinical Trials Network in the U.S., the results were even more striking, with a median survival for African-American men of 21 months versus 20 months for Caucasian men,” Dr. Halabi said. The risk of death in the adjusted analysis was 24% lower for African-American men than for Caucasian men (HR 0.76; p<.0001).

While the percentage of African-Americans as a proportion of the U.S. population is 14%, only 6% of the men in these phase III trials were African-American, she noted.

Higher numbers needed in trials

“New methodology for enrolling higher numbers of African-American men should be actively pursued and vigorously implemented so minority groups are well represented on trials,” she said, adding that because the results were obtained from clinical trials, they cannot be generalized to the U.S. population.

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Robert Dreicer, MD, associate director for clinical research and deputy director of the University of Virginia Cancer Center, Charlottesville,who was not involved in the study, commented, “I would argue that what this tells us is pretty striking… that African-American men have potentially better survival by getting conventional therapy. I think access to care is emphasized here. What this says is that when we treat African-American men with prostate cancer, they do well.”

Dr. Halabi said that her group is planning genomic analyses to evaluate if biologic variations might explain differences in outcomes by race.

Dr. Halabi is a consultant/adviser for Bayer, Eisai, and Tokai Pharmaceuticals, and has received travel, accomodations, and expenses from Bayer. For full disclosures, see bit.ly/2L6ABFg.