Gene breakthrough lifts hope of prostate cancer screening for every man

A set of 12 genes that are linked to prostate tumours has been identified, raising the prospect of a revolution in screening for the most common male cancer.

The discoveries by three research teams, one based in Britain, have doubled the known tally of genes that influence the disease, which is diagnosed in 35,000 British men each year and kills 10,000. They could help the development of tests that reveal those who have the highest inherited risk, and lead to new treatments.

The findings should enable doctors to offer genetic profiling to every middle-aged man, so that those with a high chance of developing prostate cancer could receive more detailed investigations that could spot tumours when they are still easily treatable.

It is already possible to screen for prostate tumours, but current methods rely on a blood test with a high error rate, which must then be confirmed with invasive biopsies that can cause impotence, infection and on rare occasions death. In Britain, such testing is recommended only to men with a family history of the disease.

The discovery of so many common genetic variants linked to the disease, each of which raises a man’s risk by between 20 and 200 per cent, will help scientists to develop a reliable test for gene combinations that are potentially damaging. This could make prostate cancer screening for every man a practical possibility. Those with a high genetic risk could then be offered regular blood tests, and biopsies if the results suggest a cause for concern.

Ros Eeles, of the Institute of Cancer Research in Sutton, southwest London, who led the British study, said that such screening could start in three to four years.

A test that identifies eight of the eighteen genes known to affect prostate cancer is being offered by deCODE Genetics, an Icelandic company that conducted one of the three new studies. Independent scientists said that it was too early to offer such a service, which deCODE is marketing for £250. “The results we have found are a breakthrough as they have identified seven new areas of the genome associated with prostate cancer risk,” Dr Eeles said. “They have the potential to be developed into a genetic test. However, we consider that marketing of tests to the public is premature.” He said that researchers needed to determine how often testing was needed, and the psychological implications.

The British team, funded by Cancer Research UK, found seven new genetic variants, six of which are very common. Another four genes – one of which was also identified by the British group – were found by a US study, and deCODE Genetics found another two. All the results are published in the journal Nature Genetics.

Professor Doug Easton, of the University of Cambridge, said: “In comparison with other cancers such as breast and lung cancer, we understand little about how prostate cancer develops. These results will greatly improve our knowledge of this disease.”

In all three studies, a new technique called genome-wide association was used to trawl the entire genetic code for variations in single DNA “letters” associated with prostate cancer. Similar studies have identified dozens of genetic variants that raise slightly the risk of developing conditions such as heart disease, diabetes and breast cancer. The biggest effect was found in a region of chromosome 3, where having two copies of a particular variant doubled the risk of prostate cancer – though this mutation is carried by only 1 per cent of men.

The other six genetic variants are much more common, carried by between 8 per cent and 72 per cent of men. Each of these genes raises the risk of prostate cancer by between 20 and 60 per cent, and the effects are cumulative. One of these mutations affects a gene called MSMB, which makes a protein that can be detected in the blood. This suggests that it could be used as a marker in diagnosis.

Chris Hiley, of the Prostate Cancer Charity, said: “A test is still to be developed based on these new genes so it will be some years before this research leads to practical benefit for men.”

Third brother is treated

Laurie Whelan, 79, had already lost his elder brother to prostate cancer when the disease was diagnosed in his younger brother a decade ago.

Mr Whelan, who had felt perfectly well and had attributed symptoms such as reduced urine flow to “not being a 21-year-old any more”, was persuaded by his family to be tested. It was just as well: he too turned out to have the disease, which was so advanced that surgery was not an option. Instead Mr Whelan, from London,was successfully treated with hormones and radiotherapy, and enrolled in the Cancer Research UK study.

“I am delighted with these results,” he said. “This seems to be an important step forward in understanding this disease. It is a very good thing for my family as I have three sons who might also be at risk. I hope it will spare them a lot of uncertainty and worry.”

Mr Whelan has not yet established if he carries any of the new genetic variants linked to prostate cancer but hopes to find out soon.

Source - The Times

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