Treatment Outcomes for Small Cell Carcinoma of the Bladder: Results From a UK Patient Retrospective Cohort Study.

Abstract

PURPOSE: Small cell carcinoma of the bladder (SCCB) is rare, accounting for less than 1% of all bladder carcinomas. It is aggressive, and outcomes are poor as a result of its early metastatic spread. Owing to its rarity, there are limitations on data to propose standardized management pathways. METHODS AND MATERIALS: We conducted a retrospective analysis of patients presenting with pure or predominant-histology SCCB to 26 institutions in the United Kingdom between 2006 and 2016. The data cutoff date was February 1, 2018. We report patient characteristics, treatment received, and subsequent clinical outcomes. RESULTS: A total of 409 eligible patients were included. Among these, 306 (74.8%) were male, the median age was 71 years (range, 35-96 years), and 189 patients (46.2%) had pure-histology SCCB. At data cutoff, 301 patients (73.6%) had died. The median overall survival (OS) was 15.9 months (95% CI, 13.2-18.7 months). Two hundred patients (48.9%) were confirmed to have bladder-confined disease (N0, M0), with a median OS of 28.3 months (95% CI, 20.9-35.8 months), versus a median OS of 12.7 months (95% CI, 10.9-14.6 months) for the 172 patients (42.1%) with confirmed N1-3 and/or M1 disease (hazard ratio [HR], 2.03; 95% CI, 1.58-2.60; P < .001). A total of 247 patients (61.5%) received primary chemotherapy, with a median OS of 21.6 months (95% CI, 15.5-27.6 months), versus a median OS of 9.1 months (95% CI, 5.4-12.8 months) in patients who did not receive primary chemotherapy (HR, 0.46; 95% CI, 0.37-0.59; P < .001). Choice of chemotherapy agent did not alter outcomes. For those with bladder-confined disease, 61 (30.5%) underwent cystectomy, and 104 (52.0%) received radiation therapy. Survival outcomes were similar for both cystectomy and radiation therapy. Only 6 patients (1.5%) were identified as having brain metastases at any time point. CONCLUSIONS: To our knowledge, this is the largest retrospective study of all-stage SCCB to date. Patients have a poor prognosis overall, but survival is improved in those able to receive chemotherapy and with organ-confined disease. Brain metastases are rare.