New research has found using MRI as a screening test alongside the prostate specific antigen (PSA) test allowed detection of cancers that would have been missed by the blood test alone.
Men over 50 in the UK can ask for a PSA test if they are experiencing symptoms or are concerned about prostate cancer. PSA is a protein produced by normal cells in the prostate and also be prostate cancer cells. A raised PSA level may suggest a problem with the prostate, which could include cancer.
The REIMAGINE study, published today in BMJ Oncology by researchers from UCL, UCLH and King's, is the first study to use MRI scans with PSA density to assess the need for further standard NHS tests.
Of the 48 participants found to have serious prostate cancer, 50% had a 'low' PSA score that would have meant they were not referred for further investigation under the current system.
For this study, researchers invited men aged 50 to 75 to have a screening MRI and PSA test. Of the 303 men who completed both tests, 48 (16%) had a positive screening MRI that indicated cancer, despite only having a median PSA density result of 1.2 ng/ml1. Two thirds of these men had lower PSA levels than the current screening benchmark of 3ng/ml, meaning they would not have been referred for further investigation by the PSA test currently in use.
After NHS assessment, 29 men (9.6%) were diagnosed with cancer that required treatment, and three men (1%) were diagnosed with low-risk cancer that did not require treatment.
Professor Caroline Moore (UCL Surgical & Interventional Science and consultant surgeon at UCLH), chief investigator of the study and NIHR Research Professor, said: "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. 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. More studies in larger groups are needed to assess this further."
Recruitment for the trial also indicated that black men responded to the screening invitation at one fifth the rate of white men, something the authors say will need to be addressed in future research.
One in four black men will get prostate cancer during their lifetime, which is double the number of men from other ethnicities. Given this elevated risk, and the fact that black men were five times less likely to sign up for the REIMAGINE trial than white men, it will be crucial that any national screening programme includes strategies to reach black men and encourage more of them to come forward for testing.
Saran Green, an author of the study and Public and Patient (PPI) Coordinator for the REIMAGINE Study
The next step towards a national prostate cancer screening programme is already underway, with the LIMIT trial being conducted with a much larger number of participants. The trial will also attempt to recruit more black men, including through mobile 'scan in a van' initiatives designed to visit communities less likely to come forward for testing in response to a GP invitation.
If LIMIT is successful, a national-level trial would also be required before prostate cancer screening becomes standard clinical practice.
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Patient and Public Involvement (PPI) Coordinator
