Comparison of clinicopathological features and prognoses of de-novo metastatic male and female bladder cancer patients.

867 Background: Bladder cancer is a common urological malignancy, but de novo metastatic disease at presentation is relatively uncommon and associated with poor prognosis. Sex-related differences in bladder cancer biology and treatment outcomes have been reported, yet data specifically focusing on de novo metastatic male and female patients remain limited. This study aimed to evaluate clinical and prognostic differences in male and female patients with metastatic bladder cancer at the time of diagnosis. Methods: This retrospective study analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database, including male and female patients diagnosed with de novo metastatic bladder cancer between 2000 and 2021. Demographic, clinicopathological, and treatment variables were compared between genders. Overall survival was evaluated using Kaplan-Meier estimates, and multivariate Cox regression analysis was performed to identify independent prognostic factors. Results: 14,785 patients who met the study criteria were included in the analysis. 82.9% of the patients were over 65 years of age. 69.6% of the patients were male. The most common pathological subtype was transitional cell carcinoma (74.3%). The most common metastatic sites were bone (30.9%), lung (29.1%), and liver (20.6%). The brain metastasis rate was 2.4%. Surgery was performed in 71% of the patients, 18.5% received radiotherapy, and 43.5% received chemotherapy. During the follow-up period, 11,358 (76.8%) patients died from bladder cancer. The 1-year, 2-year, and 3-year cancer-specific survival rates were 30.9%, 16.1%, and 11% in women, and 35.6%, 19%, and 13% in men, respectively. Median overall survival was 6 months (95% CI, 5.6-6.3) in women and 7 months (95% CI, 5.7-7.2) in men, and this difference was statistically significant (Log-rank test, p < 0.001). Male and female patients were compared in terms of clinicopathological features, and differences were found in both groups in terms of age (p < 0.001), race (p < 0.001), origin (p < 0.001), and pathological subtype (p < 0.001). There were some differences between the two groups in the treatment approaches and distribution of metastatic foci; surgery (p < 0.001), radiotherapy (p = 0.368), chemotherapy (p < 0.001), bone metastases (p < 0.001), brain metastases (p = 0.804), liver metastases (p = 0.204), and lung metastases (p = 0.046). Conclusions: Female patients with de novo metastatic bladder cancer were older and more frequently of Black race, Spanish-Hispanic-Latino origin. Pathological subtypes other than transitional cell carcinoma were detected more frequently. Older age in females influenced treatment choice. The rate of lung metastases at diagnosis was higher, bone metastases were lower, and the disease had a poorer prognosis than in males.