Upgrading of Gleason score 6 prostate cancers on biopsy after prostatectomy in the low and intermediate tPSA range

When offering watchful waiting or active monitoring protocols to prostate cancer (PCa) patients, differentiation between Gleason scores (GS) 6 and 7 at biopsy is important. However, upgrading after prostatectomy is common. We investigated the impact of different PSA levels on misclassification in the PSA range of 2-3.9 and 4-10 ng ml(-1). A total of 448 patients with GS 6 PCa on prostate biopsy were evaluated by comparing biopsy and prostatectomy GS. Possible over diagnosis was defined as GS <7, pathological stage pT2a and negative surgical margins, and possible under diagnosis was defined as pT3a or greater, or positive surgical margins; the percentage of over- or under diagnosis was determined for correctly and upgraded tumors after prostatectomy. A match between biopsy and prostatectomy GS was found in 210 patients (46.9%). Patients in the PSA range of 2.0-3.9 and 4.0-10.0 ng ml(-1) were upgraded in 32.6 and 44.0%, respectively. Over diagnosis was more common than under diagnosis (23.2% vs 15.6%). When upgraded there was a significant increase in under diagnosis. As almost 40% of GS 6 tumors on biopsy are GS 7 or higher after surgery with a significant rise in under diagnosis there is a risk of misclassification and subsequent delayed or even insufficient treatment, when relying on favorable biopsy GS.