DNA tests to identify men at risk of prostate cancer

Researchers at the Institute of Cancer Research (ICR) are to trial a DNA saliva test in GP practices in London to identify men at high risk of prostate cancer and evaluate whether advice or preventative treatment could reduce cases of prostate cancer among those found to have the highest inherited risk.

The trial is based on the results from a major study published in Nature Genetics (https://www.nature.com/articles/s41588-018-0142-8) identifying new genetic variations in the DNA code that increase the risk of prostate cancer.

The study used a new DNA analysis – the ‘Oncoarray’, to compare more than half a million single-letter changes in the DNA code of nearly 80 000 men with prostate cancer and more than 61 000 men without the disease.

The researchers identified 63 new variants in DNA which, when inherited, increased the risk of prostate cancer.

They believe that following the new study, they can now account for almost 30% of a man’s inherited risk of prostate cancer – which may be enough to start using the information in practical testing strategies.

By combining these new single letter genetic variants with more than 100 others previously linked to prostate cancer they have developed a test to identify men at highest risk of developing the disease during their lifetime.

The 1 per cent of men at highest risk are 5.7 times more likely than the general population to develop prostate cancer – taking the absolute risk from around 1 in 11 to 1 in 2.

And the top 10 per cent in the population risk distribution were 2.7 times more likely to develop the disease than the general population – corresponding to a risk of almost one in four.

Ros Eeles, Professor of Oncogenetics at the ICR, says: ‘By looking at the DNA code of tens of thousands of men in more depth than ever before, we have uncovered vital new information about the genetic factors that can predispose someone to prostate cancer, and, crucially, we have shown that information from more than 150 genetic variants can now be combined to provide a readout of a man’s inherited risk of prostate cancer.

‘If we can tell from testing DNA how likely it is that a man will develop prostate cancer, the next step is to see if we can use that information to help prevent the disease.’

The initial study will take place in three GP practices and if successful be expanded to up to 5000 patients next year.

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