Study Refines Racial Risk Stratification in Prostate Cancer

Walter Rayford, MD, PhD, MBA

Despite similar clinical presentations, there are disparities in risk stratification and outcomes between African-American and Caucasian patients with prostate cancer, explained Walter Rayford, MD, PhD, MBA.

For example, in a recent study, investigators evaluated the usefulness of adding a commercially available cell cycle progression (CCP) score, Prolaris, to improve risk stratification in a community-based, African-American patient population. Tissue samples from African-American (n = 150) and Caucasian men (n = 60) were obtained from a single community urologic oncology practice in Memphis, Tennessee, and evaluated with a CCP panel.

Based on the clinical parameters, of the 150 African-American men evaluated, 20% were classified as low-risk, 40% were classified as intermediate-risk, and 40% were classified as high-risk. Of the 60 Caucasian men evaluated, 42% were low-risk, 42% were intermediate-risk, and 17% were high-risk.

However, when re-evaluating the African-American patients using the CCP score, 30% of patients’ disease were determined to be more aggressive than the clinical low-risk category. Similarly, 21.67% and 23.3% of the patients were more aggressive than the intermediate-risk and high-risk categories, respectively. When compared with the Caucasian cohort, 12% of low-risk patients, 8% of the intermediate-risk patients, and 10% of high-risk patients were found to be more aggressive disease by the CCP score.

Overall, 24% of African-American patients were reclassified to a higher risk by CCP score compared with 10% of Caucasian men. When the mean CCP score in the African-American population was compared with the Caucasian population, the mean CCP score in the American Urological Association (AUA) low-risk was 3.2 versus 2.9, 3.4 versus 3.2 in the AUA intermediate-risk group; and 3.8 versus 3.5 in the AUA high-risk category, respectively.

Although there was a higher mean CCP score in the African-American population, the difference between the African-American and Caucasian men was not statistically significant (P = .064 for low-risk; P = .204 for intermediate-risk; and P = .209 for high-risk).

“Despite the fact that African-American and Caucasian patients have very similar clinical presentations, the mechanism of their prostate cancer can be very different. That is a key finding that we have been able to report on,” said Rayford, a urologic oncologist with the Urology Group and associate professor of medicine at the University of Tennessee West Cancer Center.

OncLive: Could you discuss the racial genomics of prostate cancer?

In an interview at the 2018 OncLive^® State of the Science Summit™ on Genitourinary Cancers, Rayford discussed the race-based study in prostate cancer and how these results can drive treatment and diagnostic strategies.Rayford: In the last decade, I have worked with a couple of pharmaceutical companies that are interested in the genomics of prostate cancer. One in particular is Myriad Genetics, and we have used their profile [tool]. It is based on a number of genes in cell cycle regulation. Using this tool, we are able to further stratify patients—particularly African-American patients—who have newly diagnosed prostate cancer. This re-stratification helps us to better select patients who are candidates for active surveillance or who require definitive treatment of their disease. We recently published this information in one of the high impact journals.

We have also worked with GenomeDx in using their tool, which looks at a number of genes expressed in prostate cancer. They use a grid of more than 40,000 genes. We have done a number of studies with this grid. This tool helps us to identify which treatment strategy might be best for every patient.

Could you elaborate on some of the differences you saw?

Is this stratification approach becoming more standardized?

Is there anything you would like to add?

We have learned a number of things. Despite the fact that African-American and Caucasian patients have very similar clinical presentations, the mechanism of their prostate cancer can be very different. That is a key finding that we have been able to report on.Based on the tool we used to re-stratify patients, it classified African-American patients to a higher risk 24% of the time. In other words, in 24% of the patients who we think have normal-volume or average growth-rate cancer, they actually have higher-risk disease. That is compared with only about 10% of Caucasian patients. Also, we were able to reclassify 50% of the Caucasian patients to a lower-risk group. This tool also helped us to stratify patients based on prostate-specific antigen score, Gleason score, and the University of California, San Francisco-Cancer of the Prostate Risk Assessment score. With these further characterizations, it provides some key insight into patients who you can conservatively follow with active surveillance or the ones you need to treat aggressively.I would not say it is standardized, but some academic centers and large urologic practices are starting to use this approach to stratify patients in the various risk categories. Our research was published earlier [in 2018]. Therefore, we do not yet have the long-term follow-up on our patients. However, this is a question that we are very interested in answering.My research underscores the importance of using these tools. Secondly, it will provide further insight into the mechanisms of prostate cancer. I also think we are headed into an area of personalized cancer medicine; this is particularly true with the research we are doing with GenomeDx. Oftentimes, for patients who we think have aggressive disease, we recommend aggressive treatment. These results are fairly critical in helping us address some of those key issues.

The goal of my work is to eliminate the gap in outcomes between African-American patients and other groups, but also to help decrease the mortality associated with all men who are diagnosed with prostate cancer.

Rayford W, Greenberger M, Bradley RV, et al. Improving risk stratification in a community-based African American population using cell cycle progression score. Transl Androl Urol. 2018; 7(suppl 4): S384—S391. doi: 10.21037/tau.2018.03.09.