Prognostic variations between 'primary' and 'progressive' muscle-invasive bladder cancer following radical cystectomy: a novel propensity score-based multicenter cohort study.

Objective: To assess prognostic differences between primary and progressive muscle-invasive bladder cancer (MIBC) following radical cystectomy.

Material And Methods: The Surveillance, Epidemiology, and End Results (SEER) database was used to abstract MIBC data following radical cystectomy from 2000 to 2019. Patients were classified as either 'Primary' MIBC (defined as the presentation of muscle-invasive disease at initial diagnosis) or 'Progressive' MIBC (defined as a non-muscle invasive disease that later progressed to MIBC). Baseline characteristics for the two groups were balanced using a propensity score overlap weight (PSOW) technique. Survival differences between the two groups were analyzed using Kaplan-Meier's plots and log-rank tests. Cox's proportional hazard regression was used to assess risk factors associated with overall survival (OS) and cancer-specific survival (CSS).

Results: Six thousand six hundred thirty-two MIBC patients were identified in the SEER database. Among them, 83.3% ( n =5658) were considered primary MIBC patients, and 16.7% ( n =974) were categorized as progressive MIBC patients. Distribution of baseline covariates, including age, sex, race, T stage, N stage, tumour grade, marital status, and chemotherapy, were well-balanced after PSOWs were applied. After stable PSOW adjustments, Kaplan-Meier survival analysis showed that the CSS for progressive MIBC [hazard ratio (HR)=1.25, 95% confidence interval (CI): 1.12-1.38, P <0.001) was poorer than the primary MIBC group. However, the difference in OS (HR=1.08, 95% CI: 0.99-1.18) was not significant ( P =0.073). Multivariate analysis also suggested that patients with progressive MIBC have significantly poorer CSS (HR=1.24, 95% CI: 1.19-1.38, P <0.001) but not OS (HR=1.08, 95% CI: 0.99-1.18, P =0.089).

Conclusion: CSS for progressive MIBC patients appears worse than for those with primary MIBC. This highlights the need to direct more resources for this patient population and particularly for high-risk cases of non-MIBC, where timely radical surgery will improve patients prognoses.