[CLINICAL OUTCOMES OF NEUROENDOCRINE CARCINOMA OF THE URINARY BLADDER].

(Objective) Patient characteristics and treatment outcomes of a rare histologic type of bladder neuroendocrine carcinoma were evaluated. (Methods) 2,133 cases of bladder cancer treated by transurethral resection of bladder tumor from August 2005 to August 2022 were histopathologically reevaluated, and clinicopathological factors, treatment methods, and prognosis of cases with a confirmed diagnosis of bladder neuroendocrine cancer were analyzed. (Results) Of 2,133 cases, 12 (0.56%) were diagnosed as neuroendocrine carcinoma. Immunohistochemical staining revealed small cell carcinoma in 10 cases (83.3%) and large cell carcinoma in 2 cases (16.7%). The median age was 79 years, and performance status 2 or higher was reported in 3 cases. Seven cases had localized cancer at the time of diagnosis, five cases had distant metastasis, and radical cystectomy was performed in four cases. Of the 3 cases who received chemotherapy, first-line platinum-based chemotherapy achieved disease control in two cases. After second-line treatment, no cases responded to pembrolizumab or enfortumab vedotin. The median overall survival (OS) of all cases was 12.5 months. The median OS of cases who underwent total cystectomy was 26 months, and that of cases who did not undergo total cystectomy was 8.2 months, showing a significant difference (p=0.05). (Conclusion) Neuroendocrine carcinoma of the urinary bladder often develops in older patients and has a poor prognosis. In cases of localized cancer, total cystectomy should be performed if possible.