Usefulness of the 2005 International Society of Urologic Pathology Gleason grading system in prostate biopsy and radical prostatectomy specimens

Abstract

OBJECTIVE To determine whether the 2005 International Society of Urologic Pathology (ISUP) Gleason Grading Consensus is clinically more useful than the conventional Gleason score (CGS), we compared the CGS and ISUP GS (IGS) of prostate needle biopsy (NB) and radical prostatectomy (RP) specimens, and evaluated the prognostic value of the ISUP GS. PATIENTS AND METHODS Of 250 patients undergoing RP, 103 with clinical stage T1–2 N0M0 were enrolled. Pathological tumour grades of NB and RP specimens were classified according to CGS by experienced pathologists in the central pathology department of our hospital, and retrospectively according to IGS by one uropathologist at the central pathology department of another hospital. All patients had RP with no neoadjuvant or adjuvant therapy. We analysed associations of CGS and IGS with biochemical recurrence‐free survival (BRFS) after RP. RESULTS The concordance rates between NB and RP specimens by CGS and IGS were 64.1% and 69.9%. Under‐grading and over‐grading rates by CGS and IGS were 28.2% and 7.8% for NB, and 27.2% and 2.9% for RP, respectively. There was a significant difference in the over‐grading rate between CGS and IGS (P = 0.026). When CGS and IGS of NB and RP specimens were compared, the concordance rates were similar, at 67% and 69.9%. The IGS was higher, by 15.6% in NB and by 20.4% in RP specimens, than CGS. Patients were divided into three groups based on IGS of NB specimens (≤6, 7 and ≥8). These groups differed significantly in BRFS after RP (P = 0.022); CGS showed no such association. CONCLUSIONS The IGS of NB specimens were significantly associated with BRFS after RP. The ISUP system is thus clinically useful for determining the most appropriate treatments for patients with early‐stage prostate cancer.