Frequency and Clinicopathological Features of Distant Metastasis of Bladder Cancer: A SEER-Based Study

Abstract Background: bladder cancer (BCa) is a common malignancy in the urinary system. But the hematogenous metastatic pattern of it was poorly explored. The aim of this study was to provide a better understanding of the prognosis of the different distant metastatic pattern from stage IV BCa patients and support for making a suitable clinical decision.Methods: The Surveillance, Epidemiology and End Result database (SEER) provided data for this study include BCa from 2010 to 2015. Kaplan–Meier method was used to evaluate the survival prognosis of patients of metastatic BCa. Cox proportional hazards regression model was utilized to analyzed risk factors. All statistical tests were two-sided.Results: At the time of diagnosis, a total of 6808 eligible patients at stage IV were extracted from SEER database. Patients who suffered metastasis to either one of the four sites occupied 25.31% (1723/6808) of BCa. Bone was the most common distant metastatic site of BCa (1225 cases), and brain metastases had the worst prognosis whose mean survival was 6.282 months. The results of univariate survival analysis presented that diagnostic age, race, gender, primary site surgery, tumor size, T stage, N stage, primary tumor site, histology, marital status and metastatic number were independent prognostic factors affecting overall survival (OS) (P<0.05). On multivariable Cox regression, squamous cell carcinoma was an independent risk factor affecting the overall survival (P < 0.05). The nomogram model was constructed to show the 1-, 3- and 5-year survival rates of patients.Conclusion: In analysis of single metastatic sites, patients with brain metastasis had the worst overall survival and lung metastasis had the best outcomes than other three distant metastases. Knowledge of these differences in metastatic patterns is helpful for clinicians to make better pre-treatment evaluation and clinical decisions.