pattern of genes switched on and off in blood cells could accurately detect which advanced prostate cancers had the worst survival.
And the researchers believe the blood test could eventually be used alongside the existing PSA test at diagnosis to select patients who need immediate treatment.
The test is unique because it assesses changes in the pattern of gene activity in blood cells triggered by a tumour elsewhere in the body.
“Prostate cancer is a very diverse disease – some people live with it for years without symptoms but for others it can be aggressive and life-threatening – so it’s vital we develop reliable tests to tell the different types apart,” said Professor Johann de Bono, leader of the prostate cancer targeted therapy team at The Institute of Cancer Research, London, and honorary consultant at The Royal Marsden NHS Foundation Trust, senior author of the study.
“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,” de Bono said.
Researchers scanned all the genes present in blood samples from 100 patients with prostate cancer at the ICR’s and The Royal Marsden’s joint Drug Development Unit in London and The Beatson West of Scotland Cancer Centre in Glasgow. They included 69 patients with advanced cancer and 31 control patients thought to have low-risk, early-stage cancer, who were being managed by active surveillance.
Using statistical modelling, they divided the patients into four groups reflecting their pattern of gene activity – the barcode. When they reviewed all the patients’ progress after almost two-and-a-half years, they found patients in one group had survived for significantly less time than patients in the others. Further modelling identified nine key active genes that were shared by all patients in the group.
They confirmed the results in another 70 US patients with advanced cancer, showing that just these nine genes could be used to accurately identify those who ultimately survived for a shorter time - 9.2 months compared with 21.6 months for patients without the gene pattern. The genes included a number involved in the immune system – suggesting the immune system was suppressed in patients whose cancers were spreading around the body.
“Whether particular genes are active or not is an important clue in identifying patients with a poor prognosis. This latest study shows that it is possible to read these patterns of gene activity like a barcode, allowing scientists to spot cancers that are likely to be more aggressive,” said Professor Alan Ashworth, chief executive of The Institute of Cancer Research.
Professor Martin Gore, medical director at The Royal Marsden, added: “Personalised medicine is the future of cancer treatment. This blood test, which reads genetic changes in prostate cancer providing a prediction of how aggressive the cancer might be, is an important development, allowing us to better tailor treatment to suit each individual.”
The test has been described in The Lancet Oncology.