Materials and Methods: This study was conducted on 117 patients who all underwent open radical prostatectomy in our institution between 2011 and 2020. Patients who received neoadjuvant therapy prior to surgery and had metastasis in lymph nodes or bones were excluded from the study.

Results: In 28 (23.9%) cases ISUP GG had upgraded in final pathology. While grade group of 81 (69.2%) patients did not change, it was downgraded in the remaining 8 (6.8%) cases. In the univariate analysis for the predictors of ISUP GG upgrade, ISUP GG distribution in biopsy pathology (OR: 0.46, 95% CI: 0.26-0.82, p=0.009), positive core fraction (PCF) (OR: 0.07, 95% CI 0.01-0.85, p=0.037), greatest positive core percentage (GPC) (OR: 0.12, 95% CI: 0.02- 0.68, p=0.016) and extraprostatic invasion extended (EPI-extended) (OR: 2.95, 95% CI: 1.16- 7.49, p=0.023) were all identified as significant factors. When these significant factors were analyzed in multivariate logistic regression analysis, biopsy ISUP grade (OR: 0.38, 95% CI: 0.18-0.79, p=0.01), greatest percentage of cancer (GPC) (OR: 0.10, 95% CI 0.01-0.78, p=0.027) and EPI-extended (OR 14.9, 95% CI:3.1-71.9, p=0.01) were shown as independent predictors.

Conclusion: ISUP GGs of a significant number of patients upgrade in the final pathology. Initial biopsy ISUP score and greatest positive core percentage in the biopsy are independent predictors of ISUP GG upgrade risk. EPI-extended was also significantly higher in ISUP upgrade group. Tumor upgrade risk should be considered prior to prostate cancer treatment.