Introduction

Gleason grading is an important predictor of oncologic outcomes in prostate cancer (PCa) patients. However, some patients with biopsy grade 1 disease might experience extreme upgrading to grade group 4-5 at radical prostatectomy (RP). We identified predictors of extreme upgrading in men treated at a single referral center

Methods

We identified 1,718 patients diagnosed with biopsy grade group 1 PCa, clinical stage T1/T2, at a single center between 1991 and 2015 and treated with RP. Extreme upgrading was defined as switching to grade 4 or 5 at final pathology. Patients were stratified according to presence of extreme upgrading. Uni- and multivariable logistic regression analyses (MVA) assessed the relationship between clinical and preoperative characteristics and the risk of extreme upgrading. Finally, 146 individuals diagnosed with biopsy grade 4-5 PCa and clinical T1 or T2 disease were abstracted from the database and compared with patients who experienced extreme upgrading at RP. Cox regression analyses evaluated differences in biochemical recurrence (BCR) rates according to grade group 1 vs. grade 4-5 PCa at biopsy after adjusting for confounders

Results

46 individuals (2.7%) were diagnosed with grade 4-5 PCa after RP. These patients were older compared to those who did not experience extreme upgrading (p<0.01) and had a significantly higher PSA at diagnosis (7.6 vs. 6.2 mg/dL; p=0.03). A lower number of cores were taken during biopsy for patients who experienced extreme upgrading at RP (12 vs 14; p<0.01). At MVA, age (OR: 1.05; p=0.03), PSA (OR: 1.04; p<0.001) and the number of cores taken (OR: 0.92; p=0.01) were independent predictors of extreme upgrading. The MVA model was used to plot predicted probability of extreme upgrading at RP according to the number of cores taken (Fig. 1). When comparing patients who experienced extreme upgrading with 146 individuals diagnosed with biopsy grade 4-5 PCa, those diagnosed with biopsy grade 1 were at lower risk of BCR (HR: 0.52; p=0.02)

Conclusions

An adequate biopsy sampling reduces the risk of underestimation of high-risk PCa. Patients with grade 1 PCa experience better outcomes compared to those diagnosed with more aggressive disease at biopsy. These considerations are of pivotal importance for more accurate risk stratification

Funding

none