Supplementary Material for: Upper Tract Urinary Cancer Recurrence after Radical Cystectomy: Risk Assessment of Intraoperative Frozen Section

<b><i>Introduction:</i></b> Upper tract urinary cancer recurrence (UTUCR) after radical cystectomy (RC) is outcome-limiting. Surgical recommendations on intraoperative performance of frozen section analysis (FSA) and management of positive ureteral margin (PUM) are lacking. <b><i>Methods:</i></b> 634 RC cases were identified (2010–2018). In patients with PUM, sequential ureteral resections up to a negative margin were performed. We investigated the accuracy of FSA, significance of PUM, and identified risk factors (RFs) to stratify patients for UTUCR. <b><i>Results:</i></b> FSA was performed in 355 patients, including a total of 693 ureters. FSA sensitivity was 0.93 and specificity 0.99. PUM conversion was possible in 52 (91.2%) cases. UTUCR occurred in 17 (4.8%) patients. Identified UTUCR RFs are non-muscle invasive bladder carcinoma (NMIBC) (OR 3.8, 95% confidence intervals [CI] 1.4–10.2, <i>p</i> = 0.008), multifocal bladder cancer in cystectomy specimen (OR 4.7, CI 1.1–20.8, <i>p</i> = 0.042), and recurrent NMIBC (OR 4.1, CI 1.5–10.9, <i>p</i> = 0.006). Risk-group stratification showed a six-fold increase in UTUCR risk (low-to high-risk). <b><i>Conclusion:</i></b> FSA is a sensitive and specific method to identify PUM. UTUCR occurs significantly more often in patients with recurrent, multifocal NMIBC at the time of RC. Patients can be risk stratified for UTUCR. In case of NMIBC-PUM, surgeons can safely opt for a kidney preserving strategy.