This is the largest analysis to date comparing black men and white men with advanced prostate cancer treated with chemotherapy, according to lead study author Susan Halabi, Ph.D., professor of biostatistics and bioinformatics at Duke University in Durham, NC. The findings will be featured in a press briefing today and presented at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting.
“By pooling data across clinical trials, this study provided a unique opportunity to evaluate how race might affect prostate cancer response to treatment,” said Dr. Halabi. “This study underscores the importance of increasing the participation of racial minorities in clinical trials. Every patient who participates in a clinical trial contributes to improving care, and all patients should have the opportunity to receive needed therapies.”In the United States, prostate cancer incidence rates are 60% higher among black men. In addition, black men are more likely to be diagnosed at a younger age, and with advanced-stage and higher-grade cancer. Despite an overall decline in prostate cancer deaths over the years, black men are twice as likely to die of the disease than white men.1,2
Each of the nine clinical trials included too few black men to be able to determine if black men benefit from docetaxel/prednisone as much as white men. Prior studies have suggested that black men with advanced prostate cancer who received treatment had shorter overall survival than white men, but evidence has been inconsistent.
About the Study: Researchers analyzed data from 8,820 men with metastatic castration-resistant prostate cancer (mCRPC) who participated in nine different randomized, phase III clinical trials. In all trials, patients received chemotherapy docetaxel with prednisone or a regimen containing docetaxel (Taxotere®) and prednisone combined with other treatments. Of the 8,820 participants, 7,528 (85%) were white, 500 (6%) were black, and the rest were Asian or an unspecified race. Only black men and white men were included in this analysis (a total of 8,028 men) in order to test a prior hypothesis that black men had a worse survival than white men.
Because black men in the study had poor-prognostic factors, such as higher prostate-specific antigen (PSA) levels and worse performance status (a measure of a patient’s general well-being and ability to perform activities of daily living), the researchers conducted a multivariable analysis that compared outcomes in black men to white men with the same prognostic factors.
Key Findings: Despite differences in prognostic factors, the median overall survival was 21 months in black men and white men. Adjusting for prognostic factors, such as patient age, performance status, site of metastasis, PSA level, alkaline phosphatase and hemoglobin levels, researchers found that black men were 19% less likely than white men to die from any cause.
Next Steps: As all patients included in this study were eligible to be enrolled in clinical trials and had access to clinical trials, the lower risk of death in black men may reflect differences in the biology of the disease, or it may be that black men have better tolerability to docetaxel-prednisone combination, noted Dr. Halabi. The researchers are planning genomic analyses to evaluate if there are biologic variations that might explain differences in outcomes by race. Meanwhile, this research highlights the importance of enrolling underrepresented populations with advanced prostate cancer in future phase III clinical trials. This study received funding from Congressionally Directed Medical Research Programs.
Study at a Glance
Disease: Advanced prostate cancer
Trial Type: Pooled analysis of data from 9 phase III clinical trials of chemotherapy plus prednisone
Patients on Trials: 8,820
Primary Finding: No difference in overall survival between black men and white men
Secondary Finding(s): Adjusting for prognostic factors, black men were 19% less likely than white men to die
References:
1. Prostate Cancer. (2017, June 19). Retrieved from https://www.cdc.gov/cancer/prostate/statistics/race.htm
2. Cancer Stat Facts: Prostate Cancer. (n.d.). Retrieved from https://seer.cancer.gov/statfacts/html/prost.html
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