Using magnetic resonance imaging to identify possible prostate cancer tumors significantly reduces the need for invasive biopsies, a Phase 3 clinical trial showed.

MRI also allows doctors to differentiate between cases of aggressive cancer that pose a grave threat and less virulent cases that do not to be treated, the European researchers reported.

The study, “MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis,” appeared in The New England Journal of Medicine. The team also presented the results at the European Association of Urology Congress in Copenhagen, March 16-20.

Prostate cancer diagnosis requires collecting small amounts of prostate tissue with a method called TRUS — for TRansrectal UltraSound guided prostate biopsy.

This is an invasive procedure that is almost like an operation. It requires obtaining 10-12 samples by inserting a probe through the rectum under local anaesthetic. TRUS is also costly, may lead to infection, and theresults are not always accurate.

The 11-country PRECISION trial (NCT02380027) looked at whether an MRI scan can decrease the need for a prostate biopsy or provide better information when a biopsy is required.

Using the Gleason score to categorize tumor aggressiveness, the scientists assessed the proportion of men diagnosed with prostate cancer that poses a serious threat and the proportion with cases that do not pose a major threat.  The non-threatening category covered cases that would not benefit from treatment.

Researchers randomly assigned 500 men to a standard biopsy or an initial MRI scan and targeted biopsy if the MRI indicated an abnormality.

Seventy-one or 28% of the 252 men who had an MRI were able to avoid a biopsy. Ninety-five or 38% of those who required a biopsy had cancer that posed a threat. This compared with 64 or 26% of the 248 men who had a TRUS procedure only.

“PRECISION is the first international multi-center randomized trial to show the benefits of using MRI at the start of the prostate cancer diagnosis process,” Veeru Kasivisvanathan, MD, PhD, the study’s first author, said in a press release.

Using MRI also led to fewer side effects. This stemmed from fewer biopsies and a more accurate depiction of a tumor’s location, Kasivisvanathan said.

“In men with a clinical suspicion of prostate cancer, we found that a diagnostic pathway including risk assessment with MRI before biopsy and MRI-targeted biopsy in the presence of a lesion suggestive of cancer was superior to the diagnostic pathway of standard [TRUS] biopsy,” the researchers wrote.

“The MRI pathway detected more harmful cancers that needed treatment, and it reduced overdiagnosis of harmless cancers, even though fewer men had a biopsy in the MRI” group, said Caroline M. Moore, MD, the study’s senior author.

“This study was the first to allow men to avoid a biopsy. If high-quality MRI can be achieved across Europe, then over a quarter of the 1 million men who currently undergo a biopsy could safely avoid it,” said Mark Emberton, MD, another study author.

As for whether more urologists should use MRI in their practice, Kasivisvanathan cautioned that doing MRIs and analyzing their results require specialist skills. “We will therefore need appropriate training for clinicians [doctors] to use the technology, and changes in health services to increase availability and capacity to perform prostate MRI,” he said.

He said MRIs can save doctors and patients money because they can reduce the need for biopsies and differentiate between cancers that pose a threat and those that do not.

“This work shows that using MRI to decide whether or not to perform a biopsy has the potential to save around a quarter of a million European men each year from going through the biopsy procedure, and so may be cost-effective in the long run,” said Hein Van Poppel, MD, PhD, adjunct secretary general of the European Association of Urology, which co-funded the study.

“MRI use also shows up small aggressive cancers at a curable stage, and allows us to delay or simply not perform biopsies for some cancers which will not turn out to be dangerous. We need time to digest the study, but at first reading it looks like it has the potential to change clinical practice,” he added.