Cutting the length of MRI scans for prostate cancer by a third would make them cheaper and more accessible without hindering accuracy, a trial has found.
It comes after a separate study involving almost 400,000 men found blood tests used to screen for the disease have little impact on reducing deaths.
Clinicians offer patients suspected of having prostate cancer an MRI scan, which is carried out in three stages.
The final step involves the patient being injected with contrast dye, which helps to enhance the images from the scan.
Removing this stage would lower costs and ensure MRIs are offered to more men, researchers from University College London (UCL) and University College London Hospitals NHS Foundation Trust said.
However, they warned it is “vital” that the scans “are of optimal diagnostic quality” if this approach is to be taken.
The Prime trial included 555 patients from 22 hospitals across 12 countries who all had a three-stage scan.
For each patient, radiologists assessed a two-step scan without the dye and the three-step scan separately.
Specialists diagnosed 29% of patients with prostate cancer using the shorter scan – the same figure as when the three-step scan images were used.
Dr Clare Allen, a lead radiologist on the trial, said the results – which have been presented at the European Association of Urology (EAU) conference in Paris – show significant prostate cancer is unlikely to be missed in the absence of a contrast scan.
“The scans will be quicker, cheaper and can be offered to more men,” she added.
“It is critical to emphasise that dropping the third part of the MRI scan is dependent on the first two parts of the scan being of high quality.
“MRI scanners in this study were optimised before they were used, so we would advise centres wishing to change to the two-part scan to ensure MRI scanners and image quality are optimised first.”
According to Cancer Research UK, there are about 52,300 new prostate cancer cases every year in the UK, equal to more than 140 a day.
Radiologist Dr Francesco Giganti, of UCL Surgery & Interventional Science and UCLH, said the three-part multiparametric MRI scan “has been a game-changer” for prostate cancer diagnosis and has spared thousands of men from “unnecessary biopsies”.
He added that the third step “takes time, involves an injection and can rarely cause some mild side effects”.
“Being able to make accurate diagnoses without the contrast stage will reduce scan time by around a third, meaning we can offer scans to more men using the same number of scanners and operators,” he added.
The trial found a two-stage MRI could also slash average costs by almost 50%.
A three-phase MRI costs £273 on average, according to researchers, while a two-phase scan would cost £145.
The trial was funded by Prostate Cancer UK and the John Black Charitable Foundation.
Dr Matthew Hobbs, director of research at Prostate Cancer UK, said: “These results mean that men could now be given quicker scans, that are just as good, don’t require an injection and are cheaper to perform.
“This will allow more men to benefit from a better, more accurate diagnosis at a lower cost to healthcare systems not only in the UK, but worldwide.
“Crucially, this team has also produced guidelines to help hospitals improve the quality of their scans to such an extent that these new, quicker scans can be just as effective as the old ones.”
It comes after a large study found blood tests that measure prostate-specific antigen (PSA) levels has little impact on reducing deaths from prostate cancer.
It could also miss some early aggressive cancers or lead to overdiagnosis, researchers from the universities of Bristol, Oxford and Cambridge found.
The Cap trial involved more than 400,000 patients between the ages of 50 and 69, almost half of whom were invited for a PSA test as part of the study.
Over a follow-up period of 15 years, the team found almost seven in 1,000 of the patients invited for screening died from prostate cancer compared to almost eight in 1,000 in the other group.
Lead author Professor Richard Martin, a Cancer Research UK scientist at the University of Bristol, said: “The key takeaway is that the small reduction in prostate cancer deaths by using the test to screen healthy men does not outweigh the potential harms.
“This results in some men going on to have invasive treatment that they don’t need, many years earlier than without screening, and the test is also failing to spot some cancers that do need to be treated.
“We need to find better ways to spot aggressive prostate cancers, so we can treat them early.”
Dr Hobbs described the findings from the Cap trial, which was published in the Journal of the American Medical Association (JAMA), as “extremely significant”.
He added that they back up the findings of previous research which showed “screening with PSA blood tests does reduce deaths from prostate cancer but that it also misses important cancers and harms men who are given treatments or biopsies they don’t need”.
“This balance of benefit and harm, and the fact that men often have no symptoms from early-stage prostate cancer, makes choosing whether or not to have a PSA blood test a complex decision,” Dr Hobbs added.
“The way we diagnose prostate cancer has improved a lot since these trials, thanks to the introduction of routine MRI scans which have made the process safer and more accurate.
“However, we still need better evidence to understand the full impact of MRI and other recent changes.”