Upgrade in Gleason score between prostate biopsies and pathology following radical prostatectomy significantly impacts upon the risk of biochemical recurrence

Abstract

Objective: •To determine the effect of an upgrade in Gleason score between initial prostate biopsy and final prostatectomy specimen on the risk of postoperative biochemical recurrence.

Patients and methods: •A total of 1629 patients with paired biopsy and radical prostatectomy histology were identified from two prospectively recorded prostate cancer databases. •Information on key clinical and pathological characteristics as well as prostate-specific antigen follow-up was recorded. •Patients who experienced an upgrade in their Gleason score were compared with corresponding patients with concordant tumours of the lower and higher grade. •Kaplan-Meier curves and multivariate models were generated to examine the impact of Gleason score upgrade on the risk of postoperative biochemical recurrence.

Results: •Overall, 466 patients (28.6%) experienced an upgrade in their Gleason score post radical prostatectomy, in 88.4% of cases involving a change in a single Gleason score point. •Patients upgraded from Gleason 6 (3 + 3) to Gleason 7 (3 + 4) had pathological characteristics that were very similar to Gleason 7 (3 + 4) concordant tumours, with an identical risk of biochemical recurrence. In contrast, patients upgraded from Gleason score 6 (3 + 3) to Gleason 7 (4 + 3) had tumours with pathological characteristics intermediate between the two concordant groups, which was mirrored by their risk of biochemical recurrence. •Patients with Gleason 7 tumours who experienced a change in the predominant pattern from 3 + 4 to 4 + 3 had tumours that resembled Gleason 7 (4 + 3) concordant tumours, with a similar risk of biochemical recurrence. In contrast, patients upgraded from Gleason 7 to Gleason >7 had tumours with intermediate pathological characteristics, and a risk of biochemical recurrence that was significantly different to concordant tumours of the lower and higher grade. •In multivariate models, a change in Gleason score was an independent predictor of biochemical recurrence in the preoperative setting only. •Although a difference in Gleason score was an independent predictor of recurrence in concordant tumours in models based on postoperative variables, an upgrade in Gleason score in discordant tumours was not, with differences in co-segregated adverse pathological characteristics being more predictive.

Conclusions: •Patients experiencing an upgrade in their Gleason score between biopsy and final specimen exhibit significantly more aggressive pathological features than corresponding concordant tumours, and a higher risk of biochemical recurrence post radical prostatectomy. •As Gleason score can be more accurately assessed preoperatively than other prognostic tumour features, continued effort is required to identify those most at risk of upgrading, and to refine biopsy strategies to reduce sampling error.