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 5.0yr (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.