MRI scans improve prostate cancer detection in screening study

22 Aug 2023

The REIMAGINE study has found that using MRI scans as a screening test alongside PSA density allows detection of cancers that would have been missed by the blood test alone. These results were published today in BMJ Oncology. 

REIMAGINE is the first study to use MRI scans with prostate specific antigen (PSA) density to assess the need for further standard 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 earlier 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 overdiagnosis and overtreatment of lower risk cancers. 

In recent years, the introduction of MRI as a first step in investigating men at higher risk of prostate cancer has spared one in four men from an unnecessary biopsy, which is invasive and can lead to complications.  

It is hoped that using MRI as a screening tool that is offered to men without them needing to ask for it could further reduce prostate cancer mortality and overtreatment. 

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/ml. 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.  

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. 

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. 

The REIMAGINE study was supported by the National Institute for Health and Care Research UCLH Biomedical Research Centre, the Medical Research Council (MRC) and Cancer Research UK (CRUK). 

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