Treatment outcomes for small cell carcinoma of the bladder: results from a UK patient retrospective cohort study

Abstract

Background: Small cell carcinoma of the bladder (SCCB) is rare, accounting for under 1% of all bladder carcinomas. It is aggressive and outcomes are poor due to early metastatic spread. Owing to its rarity, there are limitations on data to propose standardised management pathways. Patients and methods: We conducted a retrospective analysis of patients presenting with pure or predominant histology SCCB to 26 UK institutions between 2006 and 2016. Data cut-off date was 1/2/2018. We report on patient characteristics, treatment received and subsequent clinical outcomes. Results: 409 eligible patients were included. 306 (74.8%) were male, median age was 71 years (range 35-96) and 189 (46.2%) had pure histology SCCB. At data cut-off, 301 patients (73.6%) have died. Median overall survival (OS) was 15.9 (95% confidence interval (CI) 13.2-18.7) months. 200 patients (48.9%), were confirmed to have bladder confined disease (N0 M0), with a median OS of 28.3 (95% CI 20.9-35.8) months, versus 12.7 (95% CI 10.9-14.6) months for 172 (42.1%) patients with confirmed N1-3 and/or M1 disease (hazard ratio 2.03, 95% CI 1.58-2.60, p=<0.001). 247 patients (61.5%) received primary chemotherapy, with a median OS of 21.6 (95% CI 15.5-27.6) months, versus 9.1 (95% CI 5.4-12.8) months in those who did not (HR 0.46, 95%CI 0.37-0.59, p=<0.001). Choice of chemotherapy agent did not alter outcomes. For those with bladder confined disease, 61 patients (30.5%) had cystectomy and 104/200 (52.0%) had radiotherapy. Survival outcomes were similar despite choice of cystectomy or radiotherapy. Only 6 patients (1.5%) were identified to have brain metastases at any time point. Conclusions: This is the largest retrospective study of all stage SCCB to date. Patients have a poor prognosis overall but with improved survival in those able to receive chemotherapy and with organ confined disease. Brain metastases are rare.