A large, retrospective study analysing five years of data from the Veterans Health Administration (VHA) found that African-American men with metastatic castration-resistant prostate cancer (mCRPC) who were treated with newer prostate cancer drugs - abiraterone acetate or enzalutamide and who had not received prior chemotherapy, lived 20% longer compared with white men who received the same treatment.
These findings will be presented at the upcoming 2019 Genitourinary Cancers Symposium in San Francisco, California.
“We’ve historically seen that prostate cancer is more common, more aggressive and more lethal in African Americans, compared with men of other racial groups,” said lead study author Megan McNamara, MD, Assistant Professor of Medicine at the Duke University School of Medicine in Durham, North Carolina. “Balancing against other health-related risks, we found that treatment with newer hormonal medicines led to a significantly greater survival for African-American men in this analysis, compared with white men.”
About the study
Researchers analysed VHA data from April 2013 to March 2018, focusing on men with prostate cancer who were age 18 or older, whose only prior treatment was surgical or medical castration.
Among men with disease that had progressed, researchers included only those who had been treated with either abiraterone acetate or enzalutamide.
These medications were approved in 2013 and 2014, respectively, for use in men with mCRPC who had not received chemotherapy.
Investigators monitored patients’ health outcomes until they either disenrolled from the VHA or died.
Altogether, the analysis included data from 2,123 white and 787 African-American men with mCRPC, with mean ages of 74 and 71, respectively.
Higher rates of hypertension, type II diabetes, and liver damage or abnormality, were seen among African-American men in the study as compared with white men in the study.
After adjusting for demographic and clinical characteristics available in the VHA database, researchers found that African-American men treated with either hormone therapy lived for a median of 30 months, compared with 26 months for white men.
This research group conducted a prospective clinical trial – called Abi Race, which explored prostate cancer outcomes in African-American men and white men treated with abiraterone acetate.
Initial findings from the Abi Race trial were presented at the 2018 ASCO Annual Meeting, demonstrating better PSA response among African-American men with mCRPC treated with abiraterone acetate, compared with white men.
Additional analyses of blood samples from that trial are ongoing to investigate whether variations in key genes involved in androgen metabolism and transport may help explain some of the biology behind racial differences in treatment response.
It is hoped that these results will lead to a better understanding of why African-American men live longer than white men when treated with certain medicines for prostate cancer and why African-American men have a higher incidence of prostate cancer than white men.
“An important goal of the study is to understand why some men respond better to certain treatments for prostate cancer than others so that we can tailor treatments more effectively,” said Dr McNamara. “Finding biomarkers that can guide the development of targeted therapies is the ultimate goal.”