Hydronephrosis modifies the association between ureteroscopy and intravesical recurrence risk after radical nephroureterectomy for upper tract urothelial carcinoma.

This study investigates whether ureteroscopy (URS) increases intravesical recurrence (IVR) risk following radical nephroureterectomy for upper tract urothelial carcinoma and identifies vulnerable patient subgroups. Previous studies did not fully clarify the impact of URS and biopsy on IVR risk, or whether the risk is elevated in specific subgroups. We retrospectively analyzed 1,483 patients who underwent radical nephroureterectomy for upper tract urothelial carcinoma at nine institutions between January 2001 and April 2024. Cox proportional hazards models identified risk factors for IVR. Subgroup analyses determined characteristics increasing recurrence susceptibility. Inverse probability of treatment weighting validated subgroup analyses results. The median follow-up period was 45.1 (IQR 21.1–79.4) months. Multivariable analysis revealed that male sex, lower clinical T stage, concomitant bladder cancer, and pathological node-negative status were significantly associated with shorter IVR-free survival and confirmed URS as an independent risk factor for recurrence (HR = 1.30, 95% CI: 1.10–1.53, P < 0.001). URS-associated recurrence risk varied most by the presence of hydronephrosis. In weight-adjusted cohorts, IVR-free survival was significantly shorter with URS compared to non-URS among patients without hydronephrosis (HR = 1.73, 95% CI: 1.35–2.21, P < 0.001), whereas no significant differences were observed among patients with hydronephrosis (HR = 1.11, 95% CI: 0.88–1.40, P = 0.4). URS was an independent risk factor for IVR, but was not associated with increased risk among patients with hydronephrosis, whereas significantly increased risk was observed in patients without hydronephrosis.