Variant histologies of urothelial carcinoma: Does it change the survival outcomes in patients managed with radical cystectomy?

Objective: To investigate the impact of variant histologies (VH) of urothelial carcinoma (UC) on survival outcomes after radical cystectomy (RC). Materials and methods: Data from 181 patients with UC treated with RC between January 2013 and December 2019 at a single tertiary care referral center were retrospectively accessed. All RC specimens were assigned by genitourinary dedicated pathologists. Overall survival (OS), disease-specific survival (DSS) and recurrence-free survival (RFS) were evaluated using the Kaplan-Meier methodology and the Cox proportional hazards regression. Results: Of 181 patients, 43.1% (n = 78) had VH, with the most common being squamous differentiation (n = 29), followed by mixed variants (n = 18), micropapillary variant (n = 10) and other subtypes (n = 21). The median (range) follow-up was 35 (18-59) months. Kaplan-Meier survival analysis shows that median OS and DS were significantly worse for VH patients (78 vs 31 months, p = 0.038; not reached vs 42 months; p = 0.016). At 5 years, VH was associated with a 12% and 14% decrease in OS and DSS, respectively. No significant statistical difference between the two groups was reached regarding RFS. However, after adjusting for confounders, such as, demographics characteristics, comorbidities and pathological features, VH were not associated with any survival outcomes. Conclusions: Our study evidenced the high incidence of bladder cancers with VH. Although clearly associated with features of more aggressive behavior, VH had not any significant impact in survival expectancies when all confounders are adjusted in multivariate analyses.