By Ann Miller Baker
When men are diagnosed with low- to intermediate-risk prostate cancer, several commercially-available tests that predict risk of progression can be used to shape treatment decisions. But a Moffitt study published in a journal of the American Association for Cancer Research calls out the need to validate the usefulness of those tests for African American patients.
Compared to European American men, African American men are 70% more likely to be diagnosed with prostate cancer and are twice as likely to die from the disease. Yet the gene expression tests used to predict prostate cancer progression were all developed and validated using predominantly European American tumor samples and data.
“Given their high risk of aggressive prostate cancer, African American men represent a patient population in critical need of prognostic tools to help them in early stages of diagnosis and treatment decision-making,” said Travis Gerke, ScD, assistant member of Cancer Epidemiology at Moffitt Cancer Center and co-author of the study.
Gerke and his Moffitt colleagues set out to see if gene expression patterns differed by race for genes included in the OncotypeDX, Prolaris and Decipher tests. All three tests are recommended by National Comprehensive Cancer Network guidelines to predict outcomes in men with low- to intermediate-risk prostate cancer.
The researchers expected that the tests’ gene expression patterns for African American men would show higher risk of progression, in keeping with their trend toward more aggressive disease. “We were surprised to find that this trend was not apparent,” said Gerke. “In fact, genes from one of the tests implied lower risk for the African American patients. This finding conflicts with likely clinical outcomes for these patients, indicating that caution is warranted when applying these tests in clinical decisions for African American men until further studies of clinical effectiveness in this patient group are available.”
That’s not to say these tests provide incorrect risk predictions for African American prostate cancer patients. Further studies with a sufficient timeframe to track disease progression and survival rates will be needed to say for certain whether or not these tests should be used for certain patient populations.
But Gerke and his co-authors urged caution in using the tests’ results to shape treatment decisions among African American men with prostate cancer. “Until the tests’ performance is validated in African American men, caution is warranted when interpreting results for these patients,” said Gerke.