Gleason grading challenges in the diagnosis of prostate adenocarcinoma: experience of a single institution

Gleason score (GS) is an important factor in determining management and outcome of prostate adenocarcinoma. A standard GS scheme was introduced by ISUP 2005 consensus conference, but there is still significant discordance in grading prostate adenocarcinomas among pathologists, especially between genitourinary-trained (GU) and non-GU pathologists. All biopsies from outside institutions referred for definitive treatment in our hospital are reviewed by a GU pathologist for confirmation and quality assurance. From 2011 to 2013, 117 consecutive prostate consults were retrieved and compared with the initial outside reports as well as final radical prostatectomy (RP) results. Follow-up prostate specific antigen (PSA) was assessed pre- and post-RP, and the results were analyzed. The overall initial GS was higher for all specimens (p = 0.007) especially for the RP cases (p = 0.002). Overall, the modal GS on initial diagnosis was GS7(4 + 3) that was downgraded to the modal GS6(3 + 3) upon review. Despite an overall substantial agreement between the non-GU and GU pathologists [ICC = 0.66], GS by GU pathologist had higher correlation with the final GS in the RP specimen [ICC = 0.62] than non-GU pathologist [ICC = 0.48]. GS on all reviewed cases were found to correlate significantly with the pre-operative PSA (p = 0.002) but the same was not true for the initial report. A non-GU pathologist is more likely to assign a higher GS than a GU pathologist, with a trend to overcall Gleason pattern 4. Considering the implications on treatment, close attention must be paid to the ISUP 2005 consensus conference recommendations.