Prognostic impact of histological subtypes in non-muscle-invasive UTUC: Propensity matched analysis.

4592 Background: Upper tract urothelial carcinoma (UTUC) is a rare malignancy with poor outcomes. While histological subtypes are known to influence bladder cancer prognosis, their impact on non-muscle-invasive UTUC remains underexplored. This study evaluates the effect of histological subtypes on survival outcomes after radical nephroureterectomy (RNU). Methods: This retrospective multicenter study included 399 patients with non-muscle-invasive UTUC who underwent RNU between August 2019 and April 2024. Patients were stratified into pure UTUC (pUTUC) and histological subtype UTUC (hsUTUC) groups. Propensity score matching (PSM) in a 1:2 ratio balanced baseline characteristics. Cancer-specific survival (CSS) was the primary endpoint; recurrence-free survival (RFS) and intravesical recurrence-free survival (IVRFS) were secondary endpoints. Kaplan-Meier curves and Cox regression models were applied for statistical analysis. Results: Among 399 patients (median age 69 years; interquartile range [IQR], 63–75), 57 (14%) had hsUTUC. After PSM (166 patients), Kaplan-Meier analysis showed comparable CSS between hsUTUC and pUTUC groups before and after matching (p > 0.05). However, hsUTUC patients exhibited significantly worse RFS and IVRFS. Multivariable Cox regression revealed hsUTUC was independently associated with worse RFS (hazard ratio [HR] 2.38, 95% confidence interval [CI] 1.29–4.36; p = 0.005) and IVRFS (HR 2.06, 95% CI 1.04–4.10; p = 0.039), but not CSS (HR 1.84, 95% CI 0.60–5.61; p = 0.283). Conclusions: Histological subtypes in non-muscle-invasive UTUC significantly increase recurrence risk but do not affect CSS. These findings highlight the need for tailored surveillance and more aggressive management strategies in hsUTUC patients. The association between histological subtypes and survival outcomes. hsUTUC vs. pUTUC Cancer-specific survival Recurrence-free survival Intravesical recurrence-free survival HR (95% CI) p value HR (95% CI) p value HR (95% CI) p value Unadjusted 1.76 (0.61-5.12) 0.297 2.30 (1.28-4.13) 0.005 1.94 (0.99-3.79) 0.053 Adjusted 1.84 (0.60-5.61) 0.283 2.38 (1.29-4.36) 0.005 2.06 (1.04-4.10) 0.039 Model was adjusted for Tumor T stage (Ta/Tis/T1), lymph node status, lymphovascular invasion, concurrent CIS, concurrent bladder cancer, and hydronephrosis.