When disease travels downstream: The effect of intravesical recurrences in patients treated for upper tract urothelial carcinoma

Abstract Background Treatment of upper tract urothelial carcinoma (UTUC) depends on risk stratification and tumour characteristics. Kidney‐sparing surgery (KSS) is preferred for low‐risk disease, whereas radical nephroureterectomy (RNU) is the standard for high‐risk UTUC. Intravesical recurrences (IVR) are common after both treatment modalities, but their impact on survival remains unclear. Objective To assess the IVR rate and cumulative hazard following UTUC treatment and oncological outcomes based on the presence of IVR during follow‐up. Second, the relation between UTUC and IVR tumour grade in patients treated with endoscopic KSS (eKSS). Methods A single‐centre study, including non‐metastatic UTUC patients treated between 2010 and 2023. Analysis was performed in a cohort of patients without a history of bladder cancer. Results In total 164 patients were selected; 85 treated with eKSS, 79 by RNU. Overall, 91 patients (55%) developed an IVR, 53 (62%) after eKSS and 38 (48%) after RNU, during a median follow‐up of 33 months (IQR 11–72). eKSS‐treated patients showed a significantly higher cumulative hazard for IVR (HR 0.6, 95% CI 0.42–0.95, p = 0.02). The CSS and MFS were comparable between patients with or without IVR during follow‐up. In patients treated by eKSS, we found IVR upgrading in 24% of patients treated with eKSS. Conclusions Patients treated by eKSS showed a higher cumulative hazard of IVR, without an impact on oncological outcomes. These findings support the use of kidney‐sparing approaches in well‐selected cases and highlight the need for proper follow‐up including the bladder and evaluate IVR preventive measures as intravesical instillations.