A study examining the differences in gene expression between African American and European American men with prostate cancer for three commercially available prostate cancer prognostic biomarker panels—Oncotype DX Prostate Score, Prolaris, and Decipher—has found that these tests may not accurately predict cancer progression in African American patients. Because of the observed racial differences across the three panels for prostate cancer prognosis, caution is warranted when using these panels in clinical decision-making for African American patients. This study by Creed et al was published in Cancer Epidemiology, Biomarkers & Prevention.

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African American men are nearly 70% more likely to be diagnosed with prostate cancer and more than twice as likely to die from the disease than their European American counterparts, according to data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program. Because commercial gene expression signatures of prostate cancer prognosis were developed and validated in predominantly European American male cohorts, limited research exists on the value of these signatures in African American men with prostate cancer.

Methodology

The researchers examined whether gene-expression patterns differed by race for the genes included in Oncotype DX Prostate, Prolaris, and Decipher commercial tests. All three tests are recommended by the National Comprehensive Cancer Network® Clinical Practice Guidelines in Oncology to predict outcomes in men with low- or intermediate-risk prostate cancer.

A total of 232 European American and 95 African American patients provided radical prostatectomy specimens. Gene expression was quantified using NanoString for 60 genes spanning the Oncotype DX Prostate, Prolaris, and Decipher panels. A continuous expression-based risk score was approximated for each. Differential expression, intrapanel coexpression, and risk by race were assessed.

Results

The researchers found that clinical and pathologic features were similar between African American and European American patients. Differential expression by race was observed for 48% of the genes measured, although the magnitudes of expression differences were small. Coexpression patterns were more strongly preserved by race group by the Oncotype DX and Decipher panels than Prolaris. Poorer prognosis was estimated in European American men compared with African American men when using Oncotype DX (P < .001), whereas negligible prognostic differences were predicted between African American patients and European American patients using Prolaris or Decipher (P > .05).

Clinical Significance

“The risk predictions for African American men from these commercial gene tests conflict with the likely clinical outcomes for these patients,” said principal study investigator Travis A. Gerke, ScD, assistant member at the Moffitt Cancer Center, in a statement. “Until the risk prediction accuracy of the tests has been thoroughly studied in African American patients, we urge caution in their use for clinical decision-making. We hope that our report escalates interest in validating the utility of genomic risk predictors in African American men.”

Dr. Gerke is the corresponding author for the Cancer Epidemiology, Biomarkers & Prevention article.

Disclosure: Funding for this study was provided by Moffitt Team Science, the V Foundation, Cancer Center Support to the Moffitt Cancer Center, the Cortner-Couch Chair for Cancer Research from the University of South Florida School of Medicine, Lesa France Kennedy, and the State of Florida. For full disclosures of the study authors, visit cebp.aacrjournals.org.