'Gene barcode' blood test can predict aggressive prostate cancers
Tuesday 9 October 2012
A blood test that reads genetic changes in blood cells like a barcode can predict how severe a man's prostate cancer is likely to be, according to two new studies.
By reading the pattern of genes switched on and off in blood cells researchers accurately identified which prostate cancers had the worst survival rates.
The researchers hope the test could eventually be used alongside the existing PSA test to select men who need more aggressive or immediate treatment.
Professor Johann de Bono, who led one of the studies at The Institute of Cancer Research (ICR), London, said: "We've shown it is possible to learn more about prostate cancers by the signs they leave in the blood, allowing us to develop a test that is potentially more accurate than those available now and easier for patients than taking a biopsy.
"Our test reads the pattern of genetic activity like a barcode, picking up signs that a patient is likely to have a more aggressive cancer. Doctors should then be able to adjust the treatment they give accordingly."
A hundred men with prostate cancer took part in a trial at the ICR and Royal Marsden's joint Drug Development Unit in London and The Beatson West of Scotland Cancer Centre in Glasgow. Scientists scanned all the genes present in the patients's blood samples.
The study, published in the Lancet Oncology, was part-funded by Cancer Research UK. It included 69 men with 'castration-resistant' cancer, which means that their disease was advanced and their tumours were no longer responsive to androgen deprivation therapy. Thirty-one men thought to have low-risk, early-stage cancer were also studied.
Using complex mathematical statistics, the researchers divided the patients into four groups based on the signature of gene activity - the 'barcode'. They measured gene activity by looking at RNA levels, the genetic material that helps turn DNA into proteins.
Almost two-and-a-half years later, they reviewed the patients' progress, and found that patients in one group had survived for significantly less time than patients in the other three. Further statistical modelling was then used to identify nine key active genes that were shared by all patients in the group.
They then confirmed their findings in another 70 patients in the US with advanced cancer, demonstrating that just these nine genes could be used to accurately identify those who survived for a shorter time. Those with the gene pattern survived for 21.6 months compared with 9.2 months for those without.
A key observation was that the gene pattern involved a number of genes used by the immune system, suggesting that a man's immune system might be involved in determining whether his prostate cancer would spread.
The second study was also published in the Lancet Oncology and was led by Professor William Oh at the Tisch Cancer Institute of Mount Sinai School of Medicine in the USA. The researchers found a signature of six genes that could be used to pinpoint men with an aggressive form of prostate cancer, in a group of 62 patients.
Professor Malcolm Mason, Cancer Research UK's prostate cancer expert, said the results were 'important'.
"Not only do they point to a group of patients with advanced prostate cancer who do particularly badly, and who therefore may need different forms of treatment, but they also point to the possible role of the immune system in influencing how a cancer might behave.
"If the present results are borne out in further studies, we may have a new way of selecting the right treatments for the right patients".
Copyright Press Association 2012
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