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 pos