A large international study, published in The New England Journal of Medicine, has shown that magnetic resonance imaging (MRI) can reduce the number of invasive prostate biopsies by up to 28%. The study authors also suggest that using MRI to target prostate biopsies leads to more harmful and fewer harmless prostate cancers being diagnosed.

Dr. Caroline Moore, Reader in Urology at University College London and senior author of the study said, "We compared standard prostate biopsy to the use of MRI, offering targeted biopsies to only those men who had a suspicious MRI. 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 arm."

Prostate cancer is currently diagnosed by examining biopsy via a procedure called TRUS (TRansrectal UltraSound guided prostate biopsy). This means taking around 10-12 samples from the prostate using a probe with a special needle. The ultrasound-guided procedure means inserting a probe into the anus under local anesthetic. It involves estimating the position of a possible tumor, it also means that tumors are often missed. 

Researchers from 23 centers randomly allocated 500 men to be examined either with a standard 10-12 core TRUS biopsy, or with an initial MRI scan followed by a targeted biopsy if the MRI showed an abnormality. The main aim was to assess what proportion of men were diagnosed with clinically significant prostate cancer and those with clinically insignificant cancer that is desirable to avoid as it doesn't benefit from treatment.

The researchers found that 71 (28%) of the 252 men in the MRI arm of the study avoided the need for a subsequent biopsy. Of those who needed a biopsy, the researchers detected clinically significant cancer in 95 (38%) of the 252 men, compared with 64 (26%) of the 248 men who received only the TRUS biopsy.

"This shows that a diagnostic pathway with initial MRI assessment followed by biopsy when required, can not only reduce the overall number of biopsies performed, but can give more accurate results than TRUS-biopsy alone. We also found that patients who had MRI had fewer side effects than those who just had the standard TRUS biopsy," explained first author Dr. Veeru Kasivisvanathan of University College London.

"The ability to perform good quality MRI and the ability to interpret the MRI information are specialist skills," said Dr. Kasivisvanathan. "In the long-term, this new diagnostic pathway can be cost-effective. Costs can be saved by the reduction in the number of men undergoing biopsy in the first place, by the earlier diagnosis of harmful cancers and in the avoidance of the diagnosis of harmless cancers"

Professor Hein Van Poppel, EAU Adjunct Secretary General, University Hospitals of the Leuven, commented, "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. 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."