The results of the PROMIS study, looking at whether MRI scans could improve prostate cancer diagnosis, were published yesterday in The Lancet. The PROMIS study found that using an MRI scan to decide which men need a prostate biopsy allows doctors to identify around a quarter of men who can safely avoid the painful procedure.
Prostate cancer is the most common cancer among men in the UK. Every year hundreds of thousands of men have a transrectal-ultrasound (TRUS) biopsy to see if they have the disease, but there are problems with this approach. TRUS biopsies miss around half of clinically important cancers, meaning men often have to have extra tests if the biopsy does not find signs of cancer. The biopsies are uncomfortable for patients, and have risks, including infections, pain, blood in urine or sperm and pain while urinating.
PROMIS tested whether a MP-MRI (multi-parametric magnetic resonance imaging) scan before biopsy could identify men who might safely avoid a biopsy. PROMIS compared the accuracy of both MP-MRI and TRUS-biopsy against another, more accurate but more invasive type of biopsy, called Template Prostate Mapping (TPM) biopsy.
Between May 2012 and December 2015, 740 men volunteered for the trial of whom 576 had all three tests - a MP-MRI scan, followed (under general anaesthetic) by a combined TPM-biopsy and TRUS-biopsy. Patients and clinicians were not aware of the results of the other tests until all tests had been completed.
PROMIS found that a MP-MRI scan before biopsy would allow at least one in four men to safely avoid a biopsy. This was because the chance that men with a negative MP-MRI had important prostate cancer was very low. The MP-MRI scan identified more than 90% of patients who had clinically important cancer, compared to TRUS biopsies which only identified 48% of the men who had clinically important cancer.
Men whose MP-MRI scan suggested may have prostate cancer will still need to have a biopsy, but the scan results may help improve the accuracy of the biopsy by showing doctors which part of the prostate to target.
If the approach recommended by PROMIS is taken up across the UK, around 40,000 men each year could avoid having biopsies and their associated side-effects. Internationally, the impact of this study could be huge, as there are around 1 million TRUS biopsies carried out in Europe, and another 1 million in the USA, each year. In order for this change to take place safely, work needs to be done to make sure the quality of the MP-MRI scans is high enough, and radiologists reading those scans have been properly trained to spot prostate cancer.
PROMIS was coordinated by the MRC Clinical Trials Unit at UCL, and took place in 11 hospitals in the UK. PROMIS was funded by the NIHR Health Technology Assessment programme (project number 09/22/67) and will be published in full in Health Technology Assessment. The views and opinions expressed therein and in any media associated with this study are those of the authors and do not necessarily reflect those of the HTA programme, NIHR, NHS or the Department of Health.