Non-Metastatic Small Cell Carcinoma of the Urinary Bladder – Clinical Outcomes from a Single Institution

Objective: This study aims to ascertain the oncological outcomes of histologically proven nonmetastatic primary small cell carcinoma of the urinary bladder in a single institution. Materials and Methods: All suitable patients were identified from a prospectively maintained cancer registry. The outcomes analysed included demographics, treatment received and survival outcomes of Overall Survival (OS) and Disease Specific Survival (DSS).The study cohort was also dichotomised to pure small cell carcinoma and mixed small cell carcinoma for an exploratory analysis to evaluate the influence of pathological subtypes on DSS and OS. Results: Thirteen patients were identified to have organ-confined small cell carcinoma of the urinary bladder. The mean age of these patients was 60 years old at diagnosis. Treatment modalities included radical cystectomy (n=3), partial cystectomy (n=2), combined chemotherapy and radiotherapy (n=4), radiotherapy alone (n=2), and no immediate treatment (n=2). At diagnosis, clinical staging consisted of organ-confined disease cT2 or better (n=11) and cT3/4 disease (n=2). The Overall Survival (OS) and Disease Specific Survival (DSS) rate of the entire cohort were 13 months and 69.2% at 1 year, 69.2% at 2 years and 61.5% at 5 years respectively. Out of the 13 patients, 5 had pure small cell carcinoma of the bladder, and 8 had mixed small cell carcinoma of the bladder. The OS was 10 months for the pure small cell carcinoma group and 97 months for the mixed small cell carcinoma group. The DSS rate was 40% at 1 year and 0% at 2 years for the pure SCCB group. The DSS rate was 75% at 1 year, 62.5% at 2 years and 37.5% at 5 years for the mixed SCCB group. Conclusion: Small cell carcinoma of the urinary bladder has a poor prognosis with aggressive progression. The presence of conventional urothelial carcinoma in SCCB appears to confer a better prognosis. This needs validation in prospective studies, and the exact mechanism requires elucidation.