Abstract
<title>Abstract</title> <p>Background The prognostic impact of time to recurrence (TTR) after radical cystectomy (RC) remains incompletely understood. We evaluated the association between TTR and post-recurrence survival (PRS) in patients with muscle-invasive bladder cancer using restricted cubic spline (RCS) analysis. Methods We retrospectively analyzed 299 patients who developed recurrence after RC between 2005 and 2022 across 10 institutions. TTR was modeled as a continuous variable using multivariable Cox regression with RCS functions. Receiver operating characteristic analyses were additionally performed to explore cutoff values. Results Median TTR was 7.8 months, and 123 patients (41.1%) developed recurrence within 6 months after RC. RCS analysis demonstrated a nonlinear association between TTR and PRS (overall p = 0.019; nonlinear p = 0.016). Mortality risk increased steeply among patients recurring within the first several postoperative months. TTR was not significantly associated with mortality when modeled linearly (hazard ratio 0.99 per month, p = 0.211). ROC analyses identified cutoff values of approximately 6 months. Patients with recurrence within 6 months had significantly worse PRS, and early recurrence remained independently associated with worse survival in multivariable analysis (hazard ratio 1.50, p = 0.015). Limitations include the retrospective design and lack of external validation. Conclusions The prognostic impact of recurrence timing after RC was concentrated within the earliest postoperative months. Recurrence within 6 months after RC was independently associated with poor PRS and may identify patients with biologically aggressive disease.</p>