Introduction: Prostate cancer is the most common malignancy of the genitourinary system in men, and the Gleason score (GS) remains the most validated prognostic indicator. Despite its critical role, discrepancies between GS values from biopsy and radical prostatectomy specimens have been reported. This study aimed to assess the concordance rate of GS and identify factors associated with upgrading or downgrading of tumor grade.

Methods: This retrospective observational cohort study reviewed the records of 133 patients diagnosed with prostate adenocarcinoma who underwent needle biopsy followed by radical prostatectomy at Shahid Beheshti Hospital, Babol, , between 2012 and 2024. All specimens were re-evaluated by a single pathologist. Statistical analyses were performed using SPSS v27.

Results: The concordance rate of Gleason scores between biopsy and prostatectomy specimens was 60.9%, with a weighted kappa coefficient of 0.656 (95% CI 0.575–0.738), indicating good agreement. Upgrading was observed in 29.3% of cases and downgrading in 9.8%. Among the clinical and pathological parameters assessed, biopsy tumor involvement percentage differed significantly across concordance categories (Kruskal-Wallis, p=0.006); age, PSA, prostate volume, time interval between biopsy and surgery, and perineural invasion showed no significant association.

Conclusion: Needle biopsy provides a moderately reliable estimate of the Gleason score, but biopsy tumor involvement percentage differed across concordance categories; this finding should not be interpreted as a confirmed directional association with upgrading. Integrating this histopathological parameter with imaging and emerging molecular and computational tools may help refine risk stratification and treatment planning.