Prostate cancer remains the second leading cause of cancer death among men in the U.S., with nearly 30,000 deaths annually. According to the latest recommendations by the American Urological Association, PSA remains the only screening test to select men with unremarkable digital rectal examination for prostate biopsies. For early-stage, low-grade disease, active surveillance — also known as watchful waiting — is considered appropriate.
Although prior studies have identified race as a contributing risk factor for prostate cancer, Kryvenko, assistant professor of pathology and urology, explained that “active surveillance criteria predictive in Caucasian men were not accurate in African American men. Despite this finding, active surveillance criteria do not include race as a variable.”
In this study, the investigators measured tumor volume in 414 men with low-risk prostate cancer. They compared clinical presentation, pathological findings, PSA and PSAD between African American and Caucasian men. Currently, physicians use the Gleason score, a standardized prostate cancer tissue grading system ranging from 2 to 10 to indicate the likelihood that a tumor will spread. A higher score means the tissue is very different from normal tissue and more likely to spread.
The researchers found that African American men with a Gleason score of 3+3=6 produce less PSA than Caucasian men with the same score. PSAD was approximately 20 percent lower in African American men compared to Caucasian men, while the tumor volume was the same.
“When low volume and low-grade cancer is detected, especially in older individuals, the decision between active surveillance and definitive therapy must be made,” said Kryvenko. “Because PSAD was about 20 percent lower in African American men — even with the same tumor volume as in Caucasians — this finding could be one of the factors why current active surveillance criteria in African Americans are not as accurate as those for Caucasians.”
This new discovery complements Kryvenko’s prior observations.
“African Americans overall not only have a higher-grade cancer at radical prostatectomy, but also their spatial distribution of cancer in the prostate is such that standard prostate biopsies may not accurately reflect more-aggressive tumor nodules,” he said. “We think there could be a constellation of factors explaining why contemporary surveillance criteria do not work well in African American men.”
University of Miami