Metastatic small‐cell carcinoma of the bladder that maintains a complete response to chemoradiation therapy

INTRODUCTION: Small‐cell carcinoma of the urinary bladder has a poor prognosis, and no standard treatment has been established. We encountered a case of a patient with metastasis in which complete response and long‐term survival were obtained by treating the primary lesion with a combination of irinotecan, carboplatin chemotherapy, and radiation therapy. CASE PRESENTATION: An 83‐year‐old man was diagnosed with a bladder tumor with liver metastasis. Small‐cell carcinoma was diagnosed via transurethral resection. Second‐line chemotherapy with irinotecan and carboplatin and irradiation of the primary lesion were significantly effective. The imaging evaluation showed a complete response. The therapeutic effect was maintained for 1 year, even after the discontinuation of chemotherapy. CONCLUSION: Irinotecan and carboplatin should be considered for the treatment of small‐cell carcinoma of the bladder. Irradiation of the primary lesion may also be useful if the extent of metastasis is low.