Objectives: To evaluate the impact of histological variants on oncological outcomes of patients with muscle-invasive bladder cancer treated with open radical cystectomy and furthermore to determine any association between survival and each histotype of bladder cancer.
Materials and methods: Data from 525 consecutive patients with muscle-invasive bladder cancer treated with radical cystectomy between January 2008 and May 2019 were collected retrospectively. The Kaplan-Meier curves and multivariable analysis addressed the role of histological variants in recurrence, cancer-specific and overall mortality between all subgroups.
Results: Of 525 patients, 131 (25.0%) showed a histological variant at radical cystectomy. With a median follow-up of 31 months, 209 (39.8%) recurrences, 184 (35.0%) cancer-related deaths and 260 (49.5%) overall deaths were reported. The presence of histological variant was associated with advanced tumour stage, the presence of concomitant carcinoma in situ, lymph node metastasis, lymphovascular invasion and positive surgical margins compared to pure urothelial bladder cancer (all p values < .008) and resulted as an independent risk factor for cancer-specific mortality (p = 0.001). Patients with a histological variant were at significantly higher risk for recurrence, cancer-specific mortality and overall mortality (all p values ≤ .001). Micropapillary, sarcomatoid or small cell differentiation was associated with reduced survival.
Conclusion: The presence of histological variants at radical cystectomy seems to be weakly associated with reduced survival compared to pure urothelial bladder cancer paired for pathologic stage. The association of histological variants with advanced and biologically aggressive tumours suggests the need for attention on the overall management of these patients, in particular for micropapillary, sarcomatoid and small cell differentiation.
Keywords: Bladder cancer; Histological variants; Mixed variants; Radical cystectomy; Urothelial carcinoma.