Introduction

To validate the 2014 ISUP Gleason grading grouping (GGG) in patients undergoing radical prostatectomy (RP), brachytherapy (BT), external beam radiation (EBRT) or no local treatment (NLT).

Methods

Using the Surveillance Epidemiology and End results (SEER)-database, we identified 242 531 patients diagnosed with nonmetastatic PCa between 2004 and 2009. Patients were grouped according to local treatment type (RP, BT, EBRT) or NLT. Biopsy and/or pathological Gleason score was categorized either in ≤6, 7 and 8-10 or according to the new grading system into GGG I (≤6), II (3+4), III (4+3), IV (8) and V (9-10). Primary endpoint was prostate cancer specific mortality (PCSM). Univariable Kaplan-Meier plots graphically depict PCSM-free survival (PCSM-FS) according to the different GGG. Multivariable Cox regression analyses adjusted for age, clinical/pathological tumor stage and lymph node status were used to compare the different GGG in each treatment cohort. The discriminant ability was assessed using the area under the Receiver Operating Characteristics (ROC) curve.

Results

Median follow-up was 76 months (IQR: 59 - 94). For all local treatment types and NLT, PCSM-FS rates differed significantly between the five strata of the 2014 ISUP GGG. All five GGG strata independently predicted PCSM. Relative to GGG II, GGG III exhibited a 1.5- to 2-fold higher PCSM rate. Similarly, across all local treatment types and NLT, GGG V patients exhibited a 2-fold higher PCSM rate than GGG IV patients. The multivariable discriminant ability of the 2014 ISUP GGG was between 0.4% to 1.1% better than the old Gleason stratification.

Conclusions

This large population-based cohort validates the ability of the new GGG to predict PCSM. The new GGG offers a modesty more accurate ability to predict PCSM-FS across all different local treatment types and NLT.

Funding

none