Feasibility and Oncological Outcomes of Segmental Ureteral Resection Versus Radical Nephroureterectomy for High-Risk Ureteral Urothelial Carcinoma

Background/Objectives: Radical nephroureterectomy (RNU) is the standard of care for high-risk upper tract urothelial carcinoma (UTUC) but causes permanent renal decline, often disqualifying patients from essential cisplatin-based adjuvant chemotherapy. Segmental ureteral resection (SUR) preserves renal function, but its safety in high-risk patients remains fiercely debated due to historical treatment selection biases and a lack of competing risk adjustments. We aimed to compare long-term oncological outcomes and postoperative renal function preservation between SUR and RNU for high-risk UTUC strictly localized to the ureter. Methods: Retrospective data from 859 patients (783 RNU, 76 SUR) with high-risk ureteral UTUC (high-grade or pathologic T2–T4) were analyzed from a 21-hospital nationwide database. Propensity score overlap weighting was implemented to achieve covariate balance. Overall survival (OS) was assessed via Cox proportional hazards regression, whereas cancer-specific survival (CSS), metastasis-free survival (MFS), and local recurrence-free survival (LRFS) were evaluated using multivariable Fine–Gray subdistribution hazard models to robustly account for the competing risk of non-cancer mortality. Results: Overlap weighting achieved excellent baseline comparability with an effective sample size of 429.5 patients per cohort. Weighted analyses demonstrated comparable long-term trajectories between SUR and RNU for OS (p = 0.62), CSS (hazard ratio [HR]: 0.94, p = 0.835), and MFS (HR: 0.88, p = 0.664). The Fine–Gray model confirmed that the surgical approach was not a significant independent predictor of local recurrence (HR: 0.74, p = 0.351). Crucially, the SUR group demonstrated a significantly lower renal function decline both at 1 month (−0.11 vs. −10.58 mL/min/1.73 m2, p < 0.001) and through final clinical follow-up (−5.33 vs. −12.49 mL/min/1.73 m2, p = 0.001). Conclusions: For meticulously selected patients with high-risk ureteral UTUC, SUR provides equivalent oncological control and survival outcomes to standard RNU. Crucially, this kidney-sparing approach significantly preserves postoperative renal function, safeguarding the physiological reserve required for patients to maintain eligibility for optimal subsequent systemic adjuvant therapies.