Clinical Significance of Squamous Differentiation in Urothelial Carcinoma of the Bladder

The prognostic value of squamous differentiation (SD) in urothelial carcinoma (UC) of the bladder is unclear. The aim of this study was to identify the clinical significance of SD in UC in terms of oncological outcomes in patients undergoing radical cystectomy (RC). We evaluated consecutive patients with muscle-invasive bladder cancer (MIBC; clinical T2-4aN0M0) treated with RC at our institution from March 2003 to March 2017. We enrolled 20 and 81 patients with UC with SD (UCSD) and pure UC, respectively. Postoperative survival outcomes were compared between the patients with UCSD and pure UC using the Kaplan-Meier method. Pre- and postcystectomy factors that influenced the overall survival (OS) and recurrence-free survival (RFS) were investigated in these patients. Multivariate Cox regression models were used to identify the predictors of OS and RFS. With a median follow-up time of 31 months, the 5-year OS rate of the UCSD and pure UC groups was 41.1% and 69.7% (P = .002) and the 5-year RFS rate was 51.8% and 59.5% (P = .027), respectively. The shape of the Kaplan-Meier curves for UCSD suggested a more rapid course of the disease within the first 2 years than observed in pure UC. Multivariate analyses suggested that SD in UC was significantly associated with OS (hazard ratio [HR]: 4.22; 95% confidence interval [CI]: 1.20-14.8; P = .024) and close to significance for a lower RFS (HR: 2.13, 95% CI: 0.74-6.15, P = .064). Our results indicate that SD may be an independent predictor of OS and RFS in UC of MIBC in patients undergoing RC.