In a recent study published by the American Association for Cancer Research, Creed and colleagues found that three common commercial gene expression tests for prostate cancer did not accurately predict the risk of disease progression in African-American patients.

Commercial gene expression tests have been gaining ground as prognostic tools. These tests work by analyzing the products of specific genes in malignant tumour tissue, such as ribonucleic acid (RNA). This helps to determine which genes are making proteins in the tumour tissue. The information can be used to guide treatment decisions for cancer by estimating the risk of recurrence and spread.

African American men at higher risk

In the US, prostate cancer is the most common cancer in men after skin cancer. Also, it is the third most common cause of cancer death in men, as reported by the American Cancer Society earlier this year. In 2018, the American Cancer Society reported that African-American men have a 70% greater risk of prostate cancer, and are more than twice as likely to die from the disease compared to European American men. Because African-American men have a high risk of aggressive prostate cancer, they represent a patient population in critical need of prognostic tools to help with the early stages of treatment decision-making.

In the study, gene expression patterns were examined to determine any differences by race. These were specifically for the genes included in three common commercial gene expression tests for prostate cancer: OncotypeDX Prostate, Prolaris, and Decipher. All three tests are recommended by the National Comprehensive Cancer Network guidelines to predict outcomes in men with low- or intermediate-risk prostate cancer.

Researchers established a baseline by measuring gene expression for all of the genes included in the prognostic tests. These showed that nearly half of the genes included in the panels were expressed at different levels in African-American men than in European American men. However, when they ran the commercial gene expression tests, no significant differences in prognosis (risk prediction) were shown by the three commercial tests.

Risk prediction conflicts with known clinical outcomes

This study highlights the fact that the risk prediction of these commercial gene tests for the African-American patient population conflicts with the known clinical outcomes for this population. Because of the observed racial differences across the three commercial gene expression tests for prostate cancer prognosis, the study urges caution when using these commercial gene tests for clinical decision-making. As there are no other prognostic tests set to launch in the near future, GlobalData anticipates the need for prognostic tools suitable for African-American patients to persist. This creates opportunities for other manufacturers to enter the prostate cancer prognostic test market.