Genetics may help explain the high risk of prostate cancer in black men, scientists say
Scientists have discovered genetic mutations that may help explain why black men are at greater risk of developing prostate cancer than men of other ethnic groups. The findings could lead to a test to identify those most at risk of developing the disease, improving survival rates.
Prostate cancer is the most common cancer among British men, with around 52,300 new cases and 12,000 deaths in Britain every year. Black men are twice as likely to be diagnosed and 2.5 times more likely to die from the disease than white men.
The reason for this disparity is unclear, but it is suspected that different levels of a protein called the androgen receptor are involved. Male hormones such as testosterone bind to it and send a signal to the cancer cells to continue growing and dividing. But while previous studies have suggested that black men have higher levels of the androgen receptor, no one has really understood why until now.
A major problem is that the genetic databases that researchers use to search for sequences that could help explain such differences are largely based on DNA from white men. “There wasn’t really a lot of information about the different frequencies of mutations in different populations to explain why black men are more likely to develop prostate cancer,” says Dr Greg Brooke, senior lecturer at the University of Essex, who co-led the research.
To overcome this problem, Dr Antonio Marco, also from the University of Essex, has developed an approach that looks for differences in the regulatory regions of genes, while taking into account recently collected information about differences in human populations.
They used this tool to analyze DNA from more than 75,000 people from diverse populations around the world, looking for regulatory regions that could explain why black men produce higher levels of androgen receptor.
The research, which has not yet been published, identified mutations in three parts of DNA that control androgen receptor levels. “These specific changes in the genetic code (mutations) are often found in men of African descent, while they are virtually absent in men of European descent,” Marco said.
They also identified hundreds of other mutations that vary by population and may influence the risk of prostate cancer in men. These discoveries could eventually lead to a genetic test that can predict which subgroup of men are most likely to develop the disease. “Such tests could revolutionize the treatment of this disease, in a similar way to what mammograms have done for breast cancer,” Brooke said.
Dr. Naomi Elster, communications director at Prostate Cancer Research, which funded the study, said: ‘For far too long people have known about the disparity between black and white men in prostate cancer and not done enough about it. This crucial research changes that and gives us some much-needed answers about why black men are at greater risk.
“We hope this will pave the way to identifying Black individuals who need more regular testing and perhaps other treatments, thereby closing the survival gap.”