Urothelial Carcinoma in Bladder Diverticula: A Multicenter Analysis of Characteristics and Clinical Outcomes

Background: Urothelial carcinoma arising in a bladder diverticulum (UCBD) is uncommon, and data on treatment and outcome are sparse. Objective: To analyze clinicopathological characteristics of UCBD and to compare outcome after radical cystectomy (RC) and partial cystectomy (PC). Design, setting, and participants: Data of 115 UCBD patients treated with RC (n = 81) or PC (n = 34) between 2000 and 2016 were collected from 11 institutional databases and were analyzed retrospectively. Median follow-up was 5.0 yr (95% confidence interval [CI]: 4.0–6.2). Outcome measurements and statistical analysis: Upstaging of tumor stage at diagnostic transurethral resection (TUR) to the RC/PC specimen was investigated. Overall survival (OS) and metastasis-free survival (MFS) after RC and PC were analyzed using Kaplan-Meier estimates, and compared using the log-rank test. Intravesical recurrences after PC were reported. A multivariable Cox proportional-hazard model was used to identify factors associated with OS. Results and limitations: There were no statistically significant differences in clinicopathological characteristics between RC and PC groups. Fifty-five percent of patients with cTa/is/1 at diagnostic TUR had ≥pT2 tumors at RC/PC. Five-year OS and MFS were, respectively, 62% and 66% for RC and 66% and 55% for PC (p = 0.9 and p = 0.6). Intravesical tumor recurrence was seen in six of 34 (18%) PC patients. In multivariable analysis, positive surgical margins and extravesical disease (≥pT2) were associated with worse OS, whereas treatment modality was not (RC: reference; PC: hazard ratio 0.94, [95% CI: 0.47–1.90], p = 0.9). Conclusions: Upstaging of UCBD was frequent, indicating an inaccuracy in clinical staging. We found no differences in OS or MFS between PC and RC groups; therefore, PC may represent a feasible surgical alternative to RC in selected UCBD patients. Patient summary: In this report, we looked at the treatment of urothelial carcinoma arising in a bladder diverticulum (UCBD). We found that bladder-sparing treatment by partial cystectomy may be an alternative to radical cystectomy in carefully selected UCBD patients. Partial cystectomy may represent a feasible alternative to radical cystectomy in carefully selected patients with urothelial cancer arising in a bladder diverticulum (UCBD). However, upstaging of UCBD is frequent, and urologists should be aware of the potential underestimation of tumor extent in UCBD.