Black men are more likely than their White or Asian counterparts to have a range of genetic changes that increase their risk of developing prostate cancer, a major new study reports.
The genetic analysis, the largest and most ethnically diverse ever conducted in prostate cancer, reveals a genetic basis for the higher risk of the disease among Black men than in other racial groups.
Testing for the genetic changes identified could pick out men at high risk of prostate cancer who might benefit from earlier and more regular screening.
A team of international researchers, led by scientists at The Institute of Cancer Research, London, and the University of Southern California in the US, pooled data from 17 large-scale studies from around the world, and analysed the genetics of more than 200,000 men of European, African, Asian and Hispanic ancestry.
The study, published in Nature Genetics today, was largely funded by the National Institutes of Health in the US, with further support from Cancer Research UK, Prostate Cancer UK and Movember.
86 new genetic changes identified
Most genetic studies of prostate cancer have focused on White men of European ancestry. However, Black men are known to be at an increased risk of being diagnosed with or dying from prostate cancer, and there is an urgent need to understand their risk profile to implement early detection strategies. The new analysis compared men with and without prostate cancer in order to identify 86 new genetic changes that influence the risk of developing the disease – bringing the total number of genetic changes associated with it to 269.
These inherited genetic changes each individually has just a small effect on the risk of developing prostate cancer, but when many are combined they can substantially increase risk. Researchers believe that the changes they have identified are part of the reason for the racial disparities seen in prostate cancer incidence.
Combining together data from all the known genetic changes linked to prostate cancer, the researchers developed an overall genetic risk score to help pick out men who have the highest levels of inherited risk.
Understanding genetic risk
When the researchers applied the risk score to different ethnic and racial groups, they found that Black men had an average genetic risk score twice as high as White men of European ancestry. Conversely, Asian men had around three quarters of the risk of White men.
The genetic risk score developed by the researchers could be used in the future to identify men who need targeted screening – an option which could particularly be considered for Black men, given their higher incidence rates.
The team also found that the impact of common genetic changes on prostate cancer risk was greater for early-onset disease, suggesting that screening should begin even earlier than age 55 – the recommended age to start prostate cancer screening according to general guidelines – for those men at high genetic risk.
Findings could help guide screening strategies
Study co-leader Professor Ros Eeles, Professor of Oncogenetics at the ICR and Consultant in Clinical Oncology and Oncogenetics at The Royal Marsden, said:
“Prostate cancer incidence differs across racial and ethnic groups and it is higher in men of African ancestry and lower in Asian men compared with men of European ancestry.
“In our new study, we’ve shown that genetic factors underlie racial and ethnic differences in the incidence of prostate cancer – and by testing for a range of genetic changes, we can identify men of African ancestry who may be at high risk and could benefit from screening.
“Our findings greatly improve our understanding of genetic risk in men of African ancestry and could help guide and transform screening strategies, so that prostate cancer in men at high risk can be caught as early as possible.”
'Reducing health inequalities'
Professor Paul Workman, Chief Executive of the ICR, said:
“It is great to see how our increasing knowledge of cancer genetics can guide targeted methods for early detection. We have known for some time that the incidence of prostate cancer is higher among Black men, but what this study does is uncover a key underlying cause of that disparity, so that we can design new screening and treatment strategies to address it. I hope this research can play an important role in reducing health inequalities among men with prostate cancer, by allowing Black men and others at high genetic risk to be identified and treated earlier.”
Study co-leader Professor Christopher Haiman, Professor of Preventive Medicine at the Keck School of Medicine and Director of the Center for Genetic Epidemiology at the University of Southern California, said:
“Through this large multiethnic analysis, we not only found new markers of risk, but also demonstrated that, by combining genetic information across diverse populations, we were able to identify a risk profile that can be applied across populations. This emphasizes the enormous value of including multiple racial and ethnic populations into genetic studies.”
Dr Matthew Hobbs, Director of Research at Prostate Cancer UK, said: “We know that black men are twice as likely to be diagnosed with prostate cancer as other men, and the results reported in this paper bring us a big step closer to working out why this is and what we should do about it.
“By studying large numbers of men, including far more black men than previously, these results significantly improve our ability to work out a man’s risk of prostate cancer across all ethnicities. This could be a crucial piece in the jigsaw that allows us to implement a future screening programme. From the very first Prostate Cancer UK grant Professor Eeles received in 1995 through to more recent funding through the Movember Centre of Excellence we are proud that she and her team have drastically improved our knowledge of the genetics underlying prostate cancer. We will continue to work together to understand how to use these findings to improve diagnosis of prostate cancer for black men and others at increased genetic risk.”