Endoscopic kidney‐sparing surgery for upper tract urothelial carcinoma in patients with a solitary kidney

Objective To evaluate cancer control, renal function trajectories, and dialysis risk in patients with a solitary kidney treated with endoscopic kidney‐sparing surgery (eKSS) for upper tract urothelial carcinoma (UTUC). Patients and Methods We conducted a retrospective multicentre cohort study including 62 consecutive patients with UTUC and a solitary kidney treated with primary eKSS between 2006 and 2024 at two tertiary referral centres. All patients underwent ureteroscopic biopsy and laser ablation followed by intensified surveillance with mandatory second‐look ureteroscopy and repeat retreatment as needed. Primary endpoints were upper tract recurrence, progression, cancer‐specific mortality, and dialysis dependency. Competing‐risk cumulative incidence functions and linear mixed‐effects models were used. Results Median age was 71 years (interquartile range [IQR] 67–77), and baseline estimated glomerular filtration rate (eGFR) was 48 mL/min/1.73 m 2 (IQR 40–70). High‐grade disease at initial ureteroscopy was present in 12 patients (19%). Over a median follow‐up of 65 months, patients underwent a median of five ureteroscopies (IQR 3–9), and 16 (26%) ultimately underwent radical nephroureterectomy. The cumulative incidence of upper tract recurrence was 70% (95% confidence interval [CI] 58–83) at 5 years. The 5‐year cumulative incidence of progression was 40% (95% CI 26–54). Cancer‐specific mortality was 20% (95% CI 7.9–32) at 5 years. Dialysis dependency occurred in 32% (95% CI 18–45) at 5 years, predominantly among patients with baseline eGFR <30 mL/min/1.73 m 2 (hazard ratio 5.68; 95% CI 1.20–27.0, P = 0.029). Mixed‐effects modelling showed a mean annual eGFR decline of 2.9 mL/min/1.73 m 2 (95% CI 1.2–4.6). Conclusions In patients with UTUC and a solitary kidney, eKSS delivered within an intensive surveillance programme provided durable renal preservation with acceptable oncological outcomes. Despite frequent recurrences requiring repeated ureteroscopic interventions, cancer‐specific mortality remained limited, supporting eKSS as a viable alternative to radical nephroureterectomy in imperative clinical settings.