Sarcomatoid Urothelial Carcinoma: A Population-Based Study of Clinicopathologic Characteristics and Survival Outcomes.

Introduction: Sarcomatoid urothelial carcinoma (SUC) is a rare and aggressive variant of bladder cancer with limited data regarding epidemiology and survival. In this study, we explored clinicopathologic factors and oncologic outcomes of patients with SUC derived from Survival, Epidemiology and End Results (SEER) database, in comparison to conventional UC (CUC).

Materials And Methods: SEER database was searched for patients with invasive (≥T1) SUC or CUC using the topography codes C67.0 to C67.9 for bladder cancer and the morphologic codes 8120/8122 for CUC/SUC respectively. Demographic/clinicopathologic/treatment/survival data were extracted. Disease-specific survival (DSS) was estimated with the Kaplan-Meier method. Chi-squared tests were used for comparative analysis and Cox proportional hazards model for identifying clinical covariates associated with DSS.

Results: A total of 569 patients with SUC and 37,740 with CUC were identified. Overall, there was a male predominant population in both cohorts, although a higher proportion of women were noted in the SUC cohort (32 vs. 25%). Patients with SUC had significantly higher incidence of non-bladder confined disease (T3/4, 37% vs. 22%) and nodal invasion (18% vs. 12%) in comparison to those with CUC (all P < .05). Median DSS was 16 months (95% CI: 12.4-19.6) in the SUC vs. 82 months (95% CI; 75.9-88.1) in the CUC cohort. Presence of SUC histology was independently associated with shorter DSS in the multivariate analysis, when adjusted for other significant clinicopathologic factors.

Conclusion: SUC was associated with advanced stage and shorter DSS compared to CUC. Further studies are needed to better understand biological underpinnings behind its aggressive behavior and the role of novel systemic treatments.