Using MRI as a screening test alongside PSA density allowed detection of cancers that would have been missed by the blood test alone, according to new research from University College London, University College London Hospitals, and King’s College London.
The REIMAGINE study, published in BMJ Oncology, is the first study to use MRI scans with prostate specific antigen (PSA) density to assess the need for further standard National Health Service (NHS) tests. Of the 29 participants found to have serious prostate cancer, 15 had a ‘low’ PSA score that would have meant they were not referred for further investigation under the current system.
Currently, men over 50 in the UK can ask for a PSA test if they are experiencing symptoms or are concerned about prostate cancer. Previous screening studies have used a PSA level of 3ng/ml or above as the benchmark for performing additional tests to look for prostate cancer, such as a biopsy.
Though previous research found that the combination of a PSA test and/or digital rectal examination, followed by a biopsy if disease is suspected, helped to reduce prostate cancer mortality by 20% after 16 years, this approach has also been linked to over-diagnosis and over-treatment of lower-risk cancers.
Moreover, the use of MRI as an initial screening tool for men at higher prostate cancer risk has prevented unnecessary biopsies for 25% of individuals, minimizing invasiveness and complications. Implementing routine MRI screenings for men, without requiring them to request it, holds potential to further decrease prostate cancer-related deaths and overmedicalization, advocates say.
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 there might be cancer, despite only having a median PSA density result of 1.2 ng/ml1. 32 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, 15 of whom had serious cancer and a PSA of less than 3ng/ml. Three men (1%) were diagnosed with low-risk cancer that did not require treatment.
Caroline Moore, MD, a professor of urology and consultant surgeon at UCLH, says: “The thought that over 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 1% of participants were ‘over-diagnosed’ with low-risk disease.”
Even so, she says, “More studies in larger groups are needed to assess this further.”
Recruitment for the trial revealed a notable disparity, with Black men responding to the screening invitation at a rate only one-fifth that of white men. The authors emphasize the necessity of addressing this discrepancy in forthcoming research efforts.
According to Saran Green, the public and patient coordinator for the REIMAGINE Study, “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 program includes strategies to reach black men and encourage more of them to come forward for testing.”
The next step toward a national prostate cancer screening program 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 an invitation from their physician. If LIMIT is successful, a national-level trial would also be required before prostate cancer screening becomes standard clinical practice.
According to Mark Emberton, MD, a professor of interventional oncology at University College London, “The UK prostate cancer mortality rate is twice as high as in countries like the U.S. or Spain because our levels of testing are much lower than other countries. Given how treatable prostate cancer is when caught early, I’m confident that a national screening program will reduce the UK’s prostate cancer mortality rate significantly. 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 10 years.”
