Tumor involvement of the trigone and urethra at the time of robot-assisted radical cystectomy is associated with adverse oncological outcomes.

Introduction: The trigone/urethra (T/U) has a distinct embryologic origin and a different histologic morphology compared to the rest of the urinary bladder. We sought to determine the association between tumors involved in the T/U and the presence of variant histology, pathologic, and oncologic outcomes in patients who underwent robot-assisted radical cystectomy (RARC).

Methods: Tumor location was classified into 2 groups: tumors in the bladder walls only, or tumors in the T/U area, with or without involvement of other bladder walls. Univariable and multivariable Cox regression models were used to determine the association between T/U with recurrence-specific (RSS), cancer-specific (CSS), and overall survival (OS).

Results: 608 patients who underwent RARC were identified, T/U involvement occurred in 191 (31%). Patients in the T/U group were more likely to have pT3/pT4 (57% vs. 42%, P < 0.01), positive surgical margins (21% vs. 9%, P < 0.01), and received salvage chemotherapy more frequently (16% vs. 8%, P < 0.01). Squamous variant histology was more frequent in the T/U group (25% vs. 17%, P = 0.02). On multivariable analysis, T/U location was independently associated with RSS (HR1.63, 95% CI 1.23-2.16, P < 0.01) and CSS (HR1.50, 95% CI 1.04-2.16, P = 0.02) but not OS.

Conclusion: Residual T/U tumor involvement was associated with a higher risk of an advanced tumor stage, positive margin, cancer recurrence, and cancer-specific death.