Prevalence of MRI lesions in men responding to a GP-led invitation for a prostate health check: a prospective cohort study.
Aim
In men with an elevated prostate-specific antigen (PSA), MRI increases the detection of clinically significant cancer and reduces overdiagnosis, with fewer biopsies. MRI as a screening tool has not been evaluated independently of PSA in a formal screening study. We present a systematic community-based evaluation of the prevalence of prostate MRI lesions in an age-selected population.
Methods and analysis
Men aged 50 to 75 years were identified from general practice (GP) practices and randomly selected to be invited for MRI and PSA screening. Men with a positive MRI or elevated PSA density (≥0.12 ng/mL 2) were recommended for standard National Health Service (NHS) prostate cancer screening.
Results
Eight GP practices sent invitations to 2096 men. 457 men (22%) responded and 303 completed both screening tests. Older white men were more likely to respond to the invitation, and black men had 20% the acceptance rate of white men.
One in six men (48/303 men, 16%) had a positive screening MRI , and another 1 in 20 men (16/303, 5%) had an elevated PSA density only. Following NHS assessment, 29 men (9.6%) were diagnosed with clinically significant cancer and 3 men (1%) with clinically insignificant cancer .
Two out of three men with a positive MRI and more than half of men with clinically significant disease had a PSA <3 ng/mL .
Conclusions Prostate MRI may have value in screening independently of PSA. These data will allow modeling the use of MRI as a primary screening tool to inform larger prostate cancer screening studies. |
Comments
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 more standard NHS testing. Of the 29 participants who had severe prostate cancer, 15 had a ’low’ PSA score which would have meant they were not referred for further investigation under the current system.
Currently, men over 50 in the UK can request a PSA test if they are experiencing symptoms or are concerned about prostate cancer. Previous screening studies have used a PSA level of 3 ng/ml or higher as a benchmark for additional testing to detect prostate cancer, such as a biopsy.
Although previous research found that the combination of a PSA test and/or a digital rectal examination, followed by a biopsy if the disease is suspected, helped reduce prostate cancer mortality by 20% after 16 years, this approach also It has been linked to overdiagnosis and overtreatment of lower-risk cancers.
In recent years, the introduction of MRI as a first step in screening men at increased risk of prostate cancer has prevented one in four men from having to undergo an unnecessary biopsy, which is invasive and can lead to complications.
It is hoped that using MRI as a screening tool offered to men without them having to request it could further reduce prostate cancer mortality and overtreatment.
For this study, researchers invited men ages 50 to 75 to have an MRI and a PSA test.
Of the 303 men who completed both tests, 48 (16%) had a positive screening MRI that indicated cancer might be present, despite having only a median PSA density result of 1.2 ng/ml. 32 of these men had PSA levels lower than the current screening benchmark of 3 ng/ml, meaning they would not have been referred for further investigation using the PSA test currently in use.
Following NHS screening, 29 men (9.6%) were diagnosed with cancer requiring treatment, 15 of whom had severe cancer and a PSA less than 3 ng/ml. 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), principal investigator of the study and NIHR research professor, said: "The idea that more than half of men with clinically significant cancer had a lower PSA at 3 ng/ml and would have been assured they were cancer-free with a PSA test alone is sobering and reiterates the need to consider a new approach to prostate cancer screening. Our results provide 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 percent of participants were "overdiagnosed" with low-risk diseases. More studies in larger groups are needed to evaluate this Deeper".
Recruitment for the trial also indicated that black men responded to the screening invitation at a rate of one-fifth that of white men, something the authors say will need to be addressed in future research.
Saran Green, author of the study from King’s College London, said: “One in four black men will have prostate cancer during their lifetime, which is double the number of men of other ethnicities. Given this elevated risk, and the fact that black men were five times less likely to participate in the REIMAGINE trial than white men, it will be critical that any national screening program include strategies to reach black men and encourage more than them to appear for the tests."
The next step towards a national prostate cancer screening program is already underway, with the LIMIT trial being carried out with a much larger number of participants. The trial will also try to recruit more black men, including through mobile “scan in a van” initiatives designed to visit communities less likely to present for the test in response to a GP invitation.
If LIMIT is successful, a nationwide trial would also be required before prostate cancer screening becomes standard clinical practice.
Professor Mark Emberton (UCL Surgical & Interventional Science and consultant urologist at UCLH), senior author of the study, said: "The death rate from prostate cancer in the UK is double that of countries such as the US and lower to other countries. Given how treatable prostate cancer is when caught early, I am confident that a national screening program will significantly reduce the death rate from prostate cancer in the UK. There is much work to do to get to that point, but I think this will be possible within the next five to ten years.”
What is already known about the topic
The European Randomized Screening for Prostate Cancer study used prostate-specific antigen (PSA) >3 ng/mL, or an abnormal digital rectal examination (DRE) to select men for a standard transrectal biopsy. The study reported a 20% reduction in prostate cancer mortality at age 16, but it was associated with significant overdiagnosis and overtreatment.
Replacing standard transrectal biopsy with MRI of the prostate and targeted biopsy in men with a lesion on MRI, in men who have a high PSA or an abnormal DRE allows at least 1 in 4 men to avoid an unnecessary biopsy and reduces overdiagnosis and overtreatment.
What does this study contribute?
We assessed the prevalence of prostate MRI lesions in men invited for a prostate health check. We found that 1 in 6 men examined had a lesion on MRI, and more than half of the men with significant cancer on biopsy had a PSA <3 ng/ml. Less than 1% of men examined were "overdiagnosed" with a low-risk disease.
How it could affect clinical practice
We should evaluate the use of an MRI-targeted approach to prostate cancer screening in a larger UK population, to assess whether it could maintain the reduction in prostate cancer mortality from formal screening, while reducing overdiagnosis and associated overtreatment by using an MRI-directed approach.
This research was supported by the UCLH Biomedical Research Center of the National Institute for Health and Care Research, the Medical Research Council (MRC) and Cancer Research UK (CRUK).
