TROP2 Expression in Bladder Transurethral Resection Specimens: Correlation With Histological Grade and Survival.

BACKGROUND/AIM: TROP2 has become a therapeutic target in urothelial carcinoma following the approval of TROP2-directed antibody-drug conjugates (ADCs), yet its expression in transurethral resection (TURBT) material remains poorly characterized. This study aimed to evaluate TROP2 protein expression using immunohistochemistry (IHC) in bladder TURBT samples and to investigate its association with histological grade, tumor stage, lymphovascular invasion (LVI), carcinoma in situ (CIS), recurrence, and survival outcomes. MATERIALS AND METHODS: A total of 79 bladder TURBT specimens were included. Histological grading was performed according to the WHO/ISUP two-tier classification system (low grade / high grade) and pathological staging was based on the AJCC/UICC TNM Classification, 8th edition. TROP2 expression was assessed using IHC and quantified using the H-score method. Statistical analyses were performed using the chi-square test, Fisher's exact test, Mann-Whitney U and Kruskal-Wallis tests, Spearman's correlation analysis, receiver operating characteristic analysis, Kaplan-Meier estimates with log-rank tests, and Cox proportional hazards regression. RESULTS: Mean age was 65.87±11.46 years (91.1% male). Mean TROP2 H-score was 173.99±48.15 (median 160.0; range 30-280). A significant negative correlation was identified between TROP2 and histological grade (rho=-0.410; p=0.0003); median H-scores were 200.0 in low-grade versus 150.0 in high-grade tumors. Receiver operating characteristic analysis yielded an area under the curve (AUC) of 0.736 (sensitivity 92.3%, specificity 45.0%; cut-off 200). No significant association was found with pT stage, LVI, CIS, recurrence, disease-free survival (log-rank p=0.886), or overall survival (log-rank p=0.752). Cox regression confirmed no independent prognostic effect on survival. CONCLUSION: TROP2 inversely correlates with histological grade in bladder TURBT specimens (AUC=0.736) and may guide pathologists in diagnostically challenging cases - limited tissue, cautery artifact, or incomplete resection - where a low H-score suggests high-grade disease. TROP2 may complement WHO/ISUP grading and serve as a candidate predictive biomarker for TROP2-targeted ADC therapies.