Giving men with suspected prostate cancer an MRI scan could improve diagnosis and save those who do not have aggressive cancers from having an unnecessary biopsy, according to a study published in The Lancet.

The study estimates that adding the extra test could help one in four (27%) men avoid an unnecessary biopsy and reduce the number of men who are over-diagnosed — diagnosed with a cancer that does not go on to cause any harm during their lifetime — by 5%.

Multi-parametric MRI (MP-MRI) scans provide information about the cancer's size, how densely packed its cells are and how well connected to the bloodstream it is, so could help differentiate between aggressive and harmless cancers. The MP-MRI scan correctly diagnosed almost all of the aggressive cancers (93%), whereas the Trans-rectal ultrasound guided (TRUS) biopsy correctly diagnosed only half (48%).

Overall, this would reduce over-diagnosis while improving detection of aggressive cancers.