Small cell carcinoma of the urinary bladder (SCCB) is rare. We report our experience using definitive external beam radiation therapy (EBRT) as part of multimodality management of SCCB.

Nineteen patients with locoregional SCCB were treated at our institution with EBRT between January 1994 and September 2012. Five patients had radiographic nodal disease. Eighteen patients received neoadjuvant (17/19; 89%) or concurrent (11/19: 58%) platinum-based chemotherapy. Acute (<90 days) and late (>90 days) toxicity was recorded using Common Terminology Criteria for Adverse Events, version 4. The Kaplan-Meier method was used for survival analysis and a log-rank test used to compare subsets of patients.

Median follow-up was 26 months. Three patients had in-bladder recurrence (2-year local recurrence, 25%), 2 being noninvasive and successfully managed with transurethral resection and the third being invasive but managed with chemotherapy alone due to simultaneous distant metastases. No patient underwent salvage cystectomy. Six patients had recurrence distantly (2-year distant recurrence, 40%), predominantly bone metastases (n = 3). No patients developed brain metastases. Actuarial 2-year disease-free and overall survival was 51% and 78%, respectively. The 2-year distant metastasis-free survival for node-negative and node-positive patients was 76% and 26%, respectively (P = .04). The 2-year incidence of distant metastases for patients receiving ≥4 cycles of doublet chemotherapy was 27%, compared with 75% with less chemotherapy (P = .01). The incidence of grade ≥2 acute and late genitourinary or gastrointestinal toxicity was 69% and 7%, respectively.

Definitive chemoradiation for locoregional SCCB is well tolerated, with encouraging local control and overall survival at 2 years.