MRI scans combined with PSA density in prostate cancer screening, pioneered by a UCL-led study, identified cases missed by PSA tests alone. The REIMAGINE study revealed that 15 participants with significant cancer had ‘low’ PSA scores, which wouldn’t trigger referrals currently. While standard methods pose overdiagnosis risks, MRI-based screening holds promise, sparing men invasive biopsies. The study also addressed the underrepresentation of black men in trials, stressing the need for inclusion in future research. If successful, a national prostate cancer screening program could emerge within a decade, reducing mortality.
Recent research carried out by UCL, UCLH, and King’s College London demonstrates that incorporating MRI scans as a complementary screening tool alongside PSA density measurements can identify prostate cancers that would have been overlooked solely by the PSA blood test. The study, known as REIMAGINE and published in BMJ Oncology, pioneers the utilization of MRI scans in conjunction with prostate-specific antigen (PSA) density to evaluate the necessity for further standard NHS tests. Among the 29 participants diagnosed with significant prostate cancer, 15 had PSA scores categorized as ‘low,’ which would not have prompted referrals for additional investigation under the current testing paradigm.
Currently, men aged 50 and above in the UK have the option to request a PSA test if they exhibit symptoms or express concerns about prostate cancer. Previous screening studies employed a PSA threshold of 3ng/ml or higher as a criterion for conducting supplementary tests, such as biopsies, to detect prostate cancer.
While prior research indicated that a combination of PSA tests and/or digital rectal examinations, followed by biopsies when warranted, led to a 20% reduction in prostate cancer mortality over 16 years, this approach was also linked to the issue of overdiagnosis and overtreatment of less aggressive cancers.
In recent years, the introduction of MRI as an initial step in assessing men at elevated risk of prostate cancer has spared one out of four men from unnecessary biopsies, which can be invasive and associated with complications.
There is optimism that incorporating MRI as a routine screening tool without necessitating individual requests could further decrease prostate cancer mortality and cases of overtreatment. In the context of this study, male participants aged 50 to 75 were invited to undergo both a screening MRI and a PSA test. Of the 303 participants who completed both tests, 48 (16%) exhibited positive results in the screening MRI suggestive of potential cancer, despite having a median PSA density result of 1.2 ng/ml. Notably, 32 of these individuals had PSA levels lower than the prevailing screening threshold of 3 ng/ml, implying they would not have been referred for further evaluation under the current PSA testing protocol.
Following assessment by the NHS, 29 men (9.6%) received cancer diagnoses requiring treatment; among them, 15 had significant cancer and PSA levels below 3 ng/ml. Additionally, three men (1%) were diagnosed with low-risk cancer, not necessitating treatment.
Professor Caroline Moore, the chief investigator of the study, remarked that the finding that over half the men with clinically significant cancer had PSA levels below 3 ng/ml is thought-provoking and underscores the necessity for rethinking the approach to prostate cancer screening. She anticipates that MRI could offer a more dependable means of identifying potentially serious cancers at an early stage while minimizing instances of ‘overdiagnosis.’
The study also revealed that black men exhibited a response rate to the screening invitation that was merely one-fifth that of white men, indicating a need for targeted efforts in future research. Saran Green, a study author from King’s College London, emphasized that one in four black men will encounter prostate cancer during their lifetime, twice the rate of men from other ethnicities. To ensure equitable participation, strategies aimed at engaging black men in the screening process must be integrated into any national screening program.
Efforts toward a national prostate cancer screening initiative are already underway, with the larger-scale LIMIT trial currently in progress. This trial will endeavor to involve more black men, employing approaches like mobile screening units to reach communities that are less likely to proactively participate.
Should the LIMIT trial prove successful, further extensive testing on a national level would be necessary before prostate cancer screening becomes standard clinical practice.
Professor Mark Emberton, a senior author of the study, conveyed confidence that the UK’s prostate cancer mortality rate, which is currently double that of countries like the US or Spain, could be significantly reduced with the establishment of a national screening program. He envisions this achievement becoming feasible within the next five to ten years, even though substantial efforts lie ahead.
The research received support from the National Institute for Health and Care Research, the UCLH Biomedical Research Centre, the Medical Research Council (MRC), and Cancer Research UK (CRUK).
