Purpose: The aim of this study was to evaluate the clinical significance of histological variants (HV) and to develop a new and simple prediction model incorporating variant forms in patients who underwent radical cystectomy for urothelial carcinoma (UC).
Materials and methods: We analyzed the data of 365 patients. We evaluated whether HV were independent predictors of survival. A new scoring model was developed using the regression coefficients from the multivariate Cox proportional hazard model. The patients were divided into three groups on the basis of the score: low-, intermediate- and high-risk. To evaluate the performance of the model, we assessed models in terms of discrimination and calibration.
Results: Patients(median age; 68.5 years) with pure form and squamous differentiation did not differ significantly but statistical analysis of the survival curves of patients with pure form and other variants revealed a statistically significant difference in terms of cancer-specific survival (CSS) (p = 0.005) and overall survival (OS) (p = 0.010). According to the new scoring model HV, the 5-yr CSS rate in each group was 93.3%, 82.9% and 50.5%, respectively. The 5-yr OS rate in each group was 90.0%, 66.3% and 33.2%, respectively. Model discrimination was good for all year models. Calibration was also adequate for the model in all year models.
Conclusions: HV were found to be important independent prognostic factors in urothelial bladder cancer. This paper presents a new prognostic model incorporating variant forms for predicting CSS and OS in these patients.
Keywords: Bladder cancer; cystectomy; outcomes; urothelial carcinoma; variant histology.