Prognostic significance of morphological patterns of Gleason grade 5 prostatic adenocarcinoma diagnosed on needle biopsy

Abstract

Grading is one of the best prognostic indicators of prostate cancer with Gleason grade 5 having the worst outcome. The prognostic influence of grade 5 patterns remains uncertain. A total of 646 prostate needle biopsy sets with Gleason score (GS) 9-10 prostatic adenocarcinoma were prospectively analysed. Patterns of grade 5 were correlated with radical prostatectomy (RP) adverse findings of high tumour volume (TV), extra-prostatic extension (EPE), seminal vesicle invasion (SVI) and lymph node involvement (LNI) in 472 and biochemical recurrence (BCR) in 338 patients after RP. Mean age and serum PSA were 69 years (range 37-91) and 26.1 ng/mL (range 1.4-1800), respectively. Gleason scores were 4+5=9 in 539 (83%), 5+4=9 in 94 (15%) and 5+5=10 in 13 cases (2%). Clusters/cords, single cells, sheets and comedocarcinoma were found in 86%, 69%, 26% and 18% with a pure pattern in 25% of cases. Comparing cases with and without sheets, there were no significant differences with RP high TV (p=0.8577), EPE (p=0.5372), SVI (p=0.5183) and LNI (p=0.4323). However, the presence of sheets predicted a significantly higher BCR rate (p=0.0033), while for tumours with single cells, the interval to BCR was significantly shorter (p<0.0001). Comparing cases with and without the other patterns, two other significant differences were found. Comedocarcinoma predicted high TV (p=0.0230) and single cells predicted EPE (p=0.0101). This study shows that all patterns currently used to assign a Gleason grade 5, including sheets, comedocarcinoma, single cells and clusters/cords, are associated with aggressive outcomes validating their inclusion in grade 5.