Not only do black men have more chance of contracting and dying of prostate cancer but they also face longer delays between diagnosis and treatment, according to a recent study, the largest ever looking at risk factors in men of African descent.
Published in the journal European Urology, the study represents an effort to correct a long-standing bias in prostate cancer research, much of which has overlooked black men.
“Most studies to date have been conducted in populations of European ancestry, creating a huge bias in our understanding of genetic risk for disease,” said Christopher Haiman, a professor of population and public health sciences at the University of Southern California and the study’s senior author.
The Washington Post reports that the researchers looked at 10 studies that included genetic data from more than 80 000 men of African descent, comparing data from 19 378 men with prostate cancer and 61 620 healthy men. When they analysed the combined data, they discovered nine new genetic variants associated with an increased risk of prostate cancer for black men.
Seven of the newly discovered variants are found primarily or exclusively in men of African descent.
One variant in the 8q24 region of the human genome, which was already known to be key in determining prostate cancer risk, appears only in men of African descent. It had the strongest association with aggressive prostate cancer of all the variants studied.
The researchers used the data to come up with a scoring system that helped identify men at particular risk and found the scores could distinguish whether they were at risk of developing aggressive or non-aggressive prostate cancers.
Eventually, scientists hope to develop a genetic screening test to help men determine their risk for prostate cancer, and to learn more about what could drive black men’s particular susceptibility to the disease.
A specific antigen found in the blood can indicate prostate cancer and a digital examination of the rectum can indicate an abnormal prostate, but no standard test exists to screen for the disease, according to the US Centres for Disease Control and Prevention (CDC).
Study details
Evidence of Novel Susceptibility Variants for Prostate Cancer and a Multiancestry Polygenic Risk Score Associated with Aggressive Disease in Men of African Ancestry
Fei Chen, Ravi Madduri, Alex Rodriguez, Burcu Darst, Alisha Chou, Xin Sheng, Anqi Wang, Jiayi Shen, Edward Saunders, Suhn Rhie, Jeannette Bensen, Sue Ingles, Rick Kittles, Sara Strom, Benjamin Rybicki, Barbara Nemesure, William Isaacs, Janet Stanford, Wei Zheng, Maureen Sanderson, Christopher Haiman.
Published in European Urology on 3 April 2023
Abstract
Background
Genetic factors play an important role in prostate cancer (PCa) susceptibility.
Objective
To discover common genetic variants contributing to the risk of PCa in men of African ancestry.
Design, setting, and participants
We conducted a meta-analysis of ten genome-wide association studies consisting of 19 378 cases and 61 620 controls of African ancestry.
Outcome measurements and statistical analysis
Common genotyped and imputed variants were tested for their association with PCa risk. Novel susceptibility loci were identified and incorporated into a multiancestry polygenic risk score (PRS). The PRS was evaluated for associations with PCa risk and disease aggressiveness.
Results and limitations
Nine novel susceptibility loci for PCa were identified, of which seven were only found or substantially more common in men of African ancestry, including an African-specific stop-gain variant in the prostate-specific gene anoctamin 7 (ANO7). A multiancestry PRS of 278 risk variants conferred strong associations with PCa risk in African ancestry studies (odds ratios [ORs] >3 and >5 for men in the top PRS decile and percentile, respectively). More importantly, compared with men in the 40–60% PRS category, men in the top PRS decile had a significantly higher risk of aggressive PCa (OR = 1.23, 95% confidence interval = 1.10–1.38, p = 4.4 × 10–4).
Conclusions
This study demonstrates the importance of large-scale genetic studies in men of African ancestry for a better understanding of PCa susceptibility in this high-risk population and suggests a potential clinical utility of PRS in differentiating between the risks of developing aggressive and nonaggressive disease in men of African ancestry.
See more from MedicalBrief archives:
Cancer deaths in South Africa on the rise
Prostate cancer mortality rate higher in men with diabetes
High-tech radiotherapy improves prostate cancer outcomes
Long-term study examines prostate cancer screening