Black men diagnosed with prostate cancer classified as low risk may have a more aggressive form of the disease than non-black men in the same category.
Almost 175,000 men in the US will be diagnosed with prostate cancer in 2019, and African Americans are disproportionately affected. When compared to their white counterparts, they are 60% more likely to develop the disease and more than twice as likely to die from it.1
All men diagnosed with prostate cancer are assigned a Gleason score of between 6 and 10 and this will determine how they are treated. The scores are based on a microscopic examination of a tumor biopsy and, the higher the number, the greater the risk of mortality.
A Gleason score of 6 signifies a favorable prognosis and a lower likelihood of death. It tends to indicate that the cancer does not necessarily require immediate treatment. This means many men in this category opt for “active surveillance”, a program of monitoring and repeated biopsies.
Researchers used information from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEEM) Program and the Prostate Active Surveillance/Watchful Waiting databases.
They analyzed the data from 192,224 men, 31,841 of whom were black, with localized prostate cancer.
The data were segmented into those with Gleason scores of 6 and those with scores of between 7 and 10. Mortality among black and non-black men in each group was then compared.
Of the men classified as Gleason score 6, there were 51 deaths among 12,707 black men at a median follow up of 36 months. This equates to 0.40%. Among 70,938 non-black patients, the number of deaths was 155, or 0.22%.
The researchers also analyzed the data of 62,736 black and 340,286 non-black men who had been followed up for 12 years.
They found the 12-year prostate cancer mortality rate in those with Gleason scores 7 or over was 5.5% in black men and 5.3% in non-black men. But the rate among Gleason 6 prostate cancers was 2.2% in black patients and 1.4% in non-black patients.
Brandon Mahal, M.D., lead researcher from the department of radiation oncology at Dana-Farber Cancer Institute which carried out the work, said the reasons for the disparity involved a number of factors.2
“It could be that Gleason 6 cancer in black men is inherently more aggressive or it may have to do with other non-tumor related factors such as how we perform biopsies. Maybe we are under-sampling their tumors and missing more aggressive disease, or there could be other socioeconomic or access to care factors that drive differences,” he observes.
The results, he adds, are an incentive for randomized, prospective trials aimed at better characterizing Gleason 6 disease in black men, as well as testing different management strategies, such as immediate treatment versus active surveillance.
Mahal BA, Berman RA, Taplin ME, Huang FW. Prostate Cancer-Specific Mortality Across Gleason Scores in Black vs Nonblack Men. JAMA 2018; 320:2479-2481.
Us TOO International (2019). Facts & Stats. Available from https://www.ustoo.org/Facts-And-Stats (accessed March 2019).
- Dana Farber Cancer Institute. (2018) Prostate cancer scoring method may underestimate mortality risk in black men [Press release]. December 18, 2018. Available from: https://www.eurekalert.org/pub_releases/2018-12/dci-pcs121818.php (accessed March 2019).