Urine test for prostate cancer offers more accurate diagnosis than blood
With PSA tests for prostate cancer offering limited accuracy, could a new urine test be a diagnosis gamechanger?
A urine test for prostate cancer has shown signs of being far more accurate than the blood screening currently used to track the disease.
Prostate cancer is the most common form of the disease among men. More than 52,000 cases are diagnosed annually in the UK and more than 12,000 men die of it.
Calls for routine screening have intensified after Sir Chris Hoy, the Olympic cyclist, announced his terminal prostate cancer diagnosis last year. However, experts agree that current testing methods are not accurate enough.
A new technique tests for proteins shed by prostate tumours that can be detected in urine. It is now a “prime candidate” to be evaluated in clinical trials planned to enrol 250,000 to 300,000 British men over the next eight years with the aim of revolutionising the way cases are identified.
Professor Rakesh Heer, chair of urology at Imperial College London and part of the Transform study team, said that the pounds 42 million project was the most important diagnosis trial in decades. It could prove “a game changer” for prostate cancer research as a whole, he added.
At present, a blood test is used to look for elevated levels of prostate-specific antigen (PSA), a protein produced by the prostate gland. However, PSA tests are known for their limited accuracy, leading to false positives and unnecessary biopsies as well as missed diagnoses. The situation is made more complicated because many cancers detected by PSA are, after further testing, classed as “indolent” – meaning that they pose no immediate harm and the best course of action is to monitor them. The urine test examines a different set of proteins. A measurement known as “area under the curve” (AUC) is used to express how effective these kinds of diagnostic tools are. An AUC score of 1 represents perfect accuracy; a score of 0.5 would indicate that a test is no better than flipping a coin at identifying positive cases.
The new test achieved an AUC score of 0.92 when used on stored samples from prostate cancer patients, according to a study published in the journal Cancer Research. PSA testing usually has an AUC between 0.65 and 0.75.
Importantly, the new test not only detected the presence of prostate cancer with high precision but could also indicate disease severity. Heer said that the results were encouraging. However, only a large clinical trial would show whether the test performs as well in the real world.
To identify prostate cancer biomarkers, researchers analysed tumour cells taken from thousands of patients. Artificial intelligence was used to pinpoint the set of proteins that were the best indicators of cancer. The researchers then used blood, prostate tissue and urine samples from a second group of patients to assess the test’s accuracy.
Mikael Benson of the Karolinska Institute in Sweden, who led the study, said: “New, more precise biomarkers than PSA can lead to earlier diagnoses and better prognoses for men with prostate cancer. They could also reduce the number of unnecessary prostate biopsies carried.
The Times
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