Targeted biopsies using magnetic resonance-transrectal ultrasound (MR-TRUS) elastic fusion can reliably predict the location and primary Gleason pattern of an index prostate tumor with 90% or greater accuracy, according to a new study. This approach, however, has limited ability to predict cancer volume.

Eduard Baco, MD, of Oslo University Hospital Aker in Oslo, Norway, and colleagues retrospectively reviewed 135 consecutive patients who sequentially underwent pre-biopsy MR, MR-TRUS image-fusion biopsy and robotic radical prostatectomy (RP) from January 2010 to September 2013. The investigators performed image-guided biopsies of MR-suspected index tumor (IT) lesions with tracking via real-time 3D TRUS. The IT lesion (the largest geographically distinct cancer focus) was independently registered on step-sectioned RP specimens.

MR-TRUS targeted biopsy accurately identified the location of the index tumor in 95% of cases the investigators reported online ahead of print in European Urology. In the remaining 5%, the index tumor was not visible on MR imaging. Each of these tumors was very small, the researchers stated. “These data suggest that MR-TRUS image-fusion biopsies could become a valuable tool in identifying the location of clinically important cancer in patients,” the authors wrote.

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Results also showed a 90% concordance of primary Gleason pattern between targeted biopsy and RP specimens.