Prostate cancer study picks out 23 risk genes

Twenty-three genetic variants associated with increased risk of prostate
cancer have been identified in a new study, bringing the total number of
susceptibility variants for the disease to 100.

Testing for
these variants could identify the one percent of men with a six-fold higher-than-average
risk of developing the disease. These men may then benefit from access to
regular screening or targeted treatment should they develop cancer.

Professor Malcolm Mason, prostate cancer expert for Cancer Research UK, which helped fund the research, said the study 'continues a quest
to unravel the complex picture of the genetic factors that increase a man's
risk of prostate cancer'.

The 77 genetic variants identified previously through genome-wide association studies were
mainly identified in populations of European decent. This study
compared genetic variants from populations with
European, African, Japanese and Latino ancestry for the first time. In total, the
researchers analysed over 10 million single nucleotide polymorphisms) in over 87,000 men.

The findings, published in the journal Nature Genetics, identified 16 new genetic variants associated
with increased prostate cancer risk in European men and seven in men of mixed
heritage. One variant was linked to increased risk of early-onset disease. The
culmination of these and previous findings mean that scientists can now explain
a third of the inherited risk of prostate cancer in European men.

Professor Ros Eeles from the Institute of Cancer Research (ICR) in the UK,
a lead author of the study, said: 'We know that there are a few
major genes that are rare and significantly affect prostate cancer risk, but
what we are now learning is that there are many other common genetic variants
that individually have only a small effect on risk, but collectively can be
very important. To use the playing cards analogy, sometimes multiple low
cards can combine to form a high risk score'.

This study adds
to a growing body of evidence supportive of genetic screening for prostate
cancer risk. Earlier this year scientists at the ICR developed a screening test to identify men who are most likely to develop an aggressive form of prostate
cancer (see BioNews 743) and researchers
in Toronto presented a genetic test to help predict the likelihood of prostate
cancer returning after treatment (see BioNews 750).

Dr Matthew Hobbs, deputy
director of research at Prostate
Cancer UK, which also helped
fund the study, said: 'There's no
doubt that genetic testing for prostate cancer is an exciting area of research.
The results of this study could take us a step closer to targeted screening by
allowing us to identify those most at risk of the disease based on the genes
that they possess'.

A clinical
trial, called BARCODE, which aims to genetically screen 5,000 men for prostate
cancer, will now investigate if the new genetic markers can improve on other
tests for the disease.

The research
was a collaboration between the ICR, the University of Cambridge and the University
of Southern California in the USA.