Is MR-visible Gleason 6 prostate cancer clinically insignificant?

Motivation: The clinical course of MR-visible Gleason 6 prostate cancer is unclear. Goal(s): We studied patients with MR-visible prostate lesions scored as Gleason 6 after MR-guided and systematic biopsy. Approach: We retrospectively analyzed the rate of Gleason grade upgrading in 95 men initially diagnosed with Gleason 6 prostate cancer in an MR-visible lesion who later underwent a second biopsy or prostatectomy. Results: Over half of MR-visible Gleason 6 lesions were upgraded to Gleason 7 with a median time to upgrade of ~2 years. Neither PSA density nor ADC value predicted subsequent upgrade. Impact: Gleason 6 prostate cancer that is MR-visible often harbors higher grade cancer. This argues for more aggressive monitoring or earlier intervention in these patients.