Introduction: Prostate adenocarcinoma exhibits significant biological heterogeneity, necessitating precise preoperative risk stratification to guide surgical management. While preoperative serum prostate-specific antigen (PSA) is a standard diagnostic marker, its quantitative relationship with definitive pathological aggressiveness requires rigorous validation. This cross-sectional study aimed to evaluate the predictive discriminative performance of preoperative serum PSA levels for histological grade groups in radical prostatectomy patients.

Material and methods: In this descriptive cross-sectional study conducted at Imam Reza Hospital, we enrolled 120 patients undergoing radical prostatectomy using convenience sampling. We evaluated the association between preoperative serum prostate-specific antigen (PSA) and pathological Gleason scores through comprehensive clinical and histopathological review. Data were statistically analyzed to determine the predictive and discriminative value of baseline PSA for high-grade adenocarcinoma, establishing its utility in clinical preoperative risk stratification.

Results: Preoperative serum PSA levels demonstrated a consistent stepwise increase with escalating Gleason scores (median 6.3 ng/mL in GS ≤6 vs. 28.3 ng/mL in GS ≥8; P<0.001). A significant positive linear correlation exists between PSA and histological grade (r=0.58; P<0.001). Furthermore, PSA showed high diagnostic accuracy for predicting high-grade pathology (AUC=0.84), with an optimal threshold of 10.2 ng/mL yielding 81.5% sensitivity and 76.8% specificity.

Conclusion: Preoperative serum PSA serves as a reliable, non-invasive biomarker for assessing histopathological aggressiveness in radical prostatectomy candidates. Integrating baseline PSA into risk-stratification algorithms enables precise identification of high-grade disease prior to intervention.