Ipsilateral recurrences after kidney-sparing surgery for upper tract urothelial carcinoma: a systematic review and meta-analysis.

Objectives: Ipsilateral recurrence is a relevant outcome measure after kidney-sparing surgery (KSS) for urothelial upper tract carcinoma (UTUC). However, studies comparing ipsilateral recurrence after segmental ureterectomy (SU) and endourological treatment (ET) are lacking. This study aimed to quantitatively assess ipsilateral recurrence in ET and SU for UTUC to inform patient counselling and future study design. Design: Systematic review and meta-analysis. Setting: A systematic literature search, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), identified relevant studies from inception to September 2024. Random-effects meta-analysis was conducted to estimate the year-wise and pooled ipsilateral recurrence separately for ET and SU. Heterogeneity was explored by subgroup and meta-regression analyses and risk of bias was assessed using Joanna Briggs Institute Critical Appraisal Checklist as well as funnel plots and Egger's regression test. Participants: Patients undergoing ET or SU included in eligible studies reporting ipsilateral recurrence outcomes. Main outcome measures: Time-to-event-derived ipsilateral recurrence probabilities and crude pooled ipsilateral recurrence proportions. Results: Seventy-four studies were included, of which 40 reported ipsilateral recurrence after ET and 34 after SU (n=3044). In 11 of these, time-to-event data were available. Time-to-event-derived ipsilateral recurrence probabilities after 4 years were 0.53 (95% CI 0.25 to 0.80) after ET and the corresponding crude ipsilateral recurrence proportion was 0.48 (95% CI 0.39 to 0.57) with considerable heterogeneity (p<0.001 Cochran's Q test). Time-to-event-derived ipsilateral recurrence probabilities after 4 years were 0.20 (95% CI 0.11 to 0.30) after SU with a crude ipsilateral recurrence proportion of 0.11 (95% CI 0.08 to 0.13) with moderate heterogeneity (p=0.20 Cochran's Q test). The estimates are derived from separate single-arm studies with differing tumour characteristics, treatment indications, surveillance protocols and other selection mechanisms that cannot be adjusted for. Results are limited by sparse reporting of numbers at risk and censoring, and lack of uniform reporting of outcome-related variables. Conclusions: Ipsilateral recurrence outcomes following SU were homogenous across studies. Direct comparative evidence evaluating ET versus SU remains lacking. Future studies should emphasise standardised reporting on outcomes and associated variables in KSS, as ipsilateral recurrence is a clinically important endpoint for patient counselling in UTUC. PROSPERO registration number: CRD42025640780.