Prognostic significance of non-urothelial carcinoma of bladder: analysis of nationwide hospital-based cancer registry data in Japan.

OBJECTIVES: To identify the prognosis of pure non-urothelial carcinoma (non-UC) of bladder and to compare them with those of pure urothelial carcinoma (UC). METHODS: We used Japan's nationwide hospital-based cancer registry data to extract histologically confirmed pure non-UC and UC cases of bladder diagnosed in 2008-2009. We estimated the 5-year overall survival (OS) by a Kaplan-Meier analysis. RESULTS: A total of 8094 patients with confirmed histological subtypes of bladder cancer were identified. The most common pure non-UC was squamous cell carcinoma (SQ, n = 192, 2.4%) followed by adenocarcinoma (AC, n = 138, 1.7%) and small cell neuroendocrine carcinoma (SmC, n = 54, 0.7%). The proportion of female patients (48%) was significantly higher in the SQ group compared with the pure UC group (P < 0.001). The 5-year OS rate of the non-UC patients was significantly worse than that of the UC patients (40 vs. 61%, P < 0.001). According to stages, the 5-year OS rates of the stage I and III non-UC patients were significantly worse than those of the UC patients (P = 0.001). Considering histologic subtypes and stages, the 5-year OS rates of the stage I SQ patients were worse than those of the AC and SmC patients (46, 68 and 64%, respectively). CONCLUSION: The prognosis of pure non-UC was worse than that of pure UC, especially in the stage I and III non-UC patients. To improve these patients' oncologic outcomes, a more aggressive surgical approach may be necessary in stage I patients with non-UC, especially in pure SQ.