Researchers have found that the PSA blood test commonly used to detect prostate cancer can be unreliable, leading to misdiagnosis. Now it’s suggested that a magnetic resonance imaging (MRI) test to screen for prostate cancer could be a much more effective means of diagnosis.
Some 47,000 men are diagnosed with prostate cancer in the UK and around 12,000 die per year in the country, according to Cancer Research UK.
At the moment, there is no screening programme for prostate cancer, despite the fact that it is the most common cancer in men. This is because the blood test which detects the levels of PSA, a protein made by the prostate gland, can give inaccurate results, leading to 1 in 7 cancers being missed, and others being misdiagnosed as having cancer. As prostate cancer treatment can have unwanted side-effects, both outcomes are a problem.
Some symptoms of prostate cancer can also be caused by an enlarged prostate, which is a benign condition.
PSA
A new study published in the BMJ Oncology journal used MRI scans alongside the prostate-specific antigen (PSA) test. The study at University College London (UCL) and King’s College London found that 15 of the 29 participants that were found to have serious prostate cancer had a low PSA score, meaning they would not have been referred for further testing based on the blood test alone.
“The thought that half the men with clinically significant cancer had a PSA less than 3 ng/ml and would have been reassured that they didn’t have cancer by a PSA test alone is a sobering one and reiterates the need to consider a new approach to prostate cancer screening,” said Caroline Moore, a urologist from UCL’s Surgical and Interventional Science department.
“Our results give an early indication that MRI could offer a more reliable method of detecting potentially serious cancers early, with the added benefit that less than one per cent of participants were ‘over-diagnosed’ with low-risk disease,” she added.
Around 16 per cent of the more than 300 participants, who were men aged 50 to 75, had an MRI scan that indicated there might be cancer, and most of them had a PSA test lower than the critical figure of 3 ng/ml.
Previous research has shown that using an MRI could reduce over-diagnosis and help nearly one in four men to avoid a biopsy, which is an invasive procedure with possible side-effects. At the moment prostate cancer testing is largely dependent on men with symptoms such as difficulty urinating going to their GP, but many men with early prostate cancer will not have symptoms. Those more at risk include black men, men over 50 and those with a family history of prostate cancer, according to Prostate Cancer UK.
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Mortality
“The UK prostate cancer mortality rate is twice as high as in countries like the US or Spain because our levels of testing are much lower than other countries,” said Mark Emberton, senior author of the study from the UCL Cancer Institute. “Given how treatable prostate cancer is when caught early, I’m confident that a national screening programme will reduce the UK’s prostate cancer mortality rate significantly,” he added. “There is a lot of work to be done to get us to that point, but I believe this will be possible within the next five to ten years”.
The authors of the study said that black men were five times less likely to sign up for the trial than white men, despite being at a higher risk for prostate cancer. Any national screening programme, they suggested, would need to encourage more black men to get tested, and possibly this could be done by taking mobile MRI scanning units into the community rather than relying on a hospital-based scanning programme.
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