Improving Risk Stratification in pT3 Upper Tract Urothelial Carcinoma: A Focus on Invasion Patterns

<b>Purpose:</b> Existing T3 subclassifications for upper tract urothelial cancer (UTUC) are limited by heterogeneity and a primary focus on renal pelvis tumors. Our study aimed to propose a novel pT3 subclassification system specifically tailored to pT3 UTUC patients. <b>Materials and Methods:</b> This study analyzed 120 pT3 UTUC cases from a Taiwanese multicenter registry, using a standardized pathology report and a single pathologist for evaluation. <b>Results:</b> Univariate analysis revealed survival differences based on existing subclassifications. Multivariate analysis identified concurrent fat and parenchyma invasion as an independent predictor of worse overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS). <b>Conclusions</b>: This study proposes a novel pT3 subclassification incorporating fat and parenchyma invasion, applicable to all UTUC sites. This subclassification may improve risk stratification, guide treatment decisions, and ultimately enhance patient outcomes.