MP72-02 OUTCOME OF PATIENTS WITH MICROPAPILLARY BLADDER CANCER TREATED WITH RADICAL CYSTECTOMY WITH/WITHOUT NEOADJUVANT CHEMOTHERAPY

INTRODUCTION AND OBJECTIVES: Muscle-invasive urothelial carcinoma of the urinary bladder (UCUB) is an aggressive disease. The standard treatment of care is radical cystectomy (RC). Trimodal bladder-preserving treatment (BPT), including transurethral resection of the bladder tumor, radiation, and chemotherapy has gained considerable interest. We sought to perform a comparative effectiveness assessment of RC vs. BPT in a stage-for-stage analysis. METHODS: We performed a retrospective cohort study of Medicare beneficiaries with non-metastatic muscle-invasive (T2eT4a, N0) UCUB treated with RC or BPT from 1991 to 2009. Following instrumental variable analysis that accounts for both measured and unmeasured confounders, multivariable Coxand competing-risks regression two-stage residual inclusions models were fitted. All analyses were stratified according to disease stage (organ-confined vs. non-organ confined). Our primary outcomes were overall survival (OS) and cancer-specific mortality (CSM). RESULTS: Overall 4168 patients with muscle-invasive UCUB were identified, where 3488 (84%) underwent RC and 680 (16%) received BPT, respectively. During the entire study span, the 5-year OS rates for RC and BPT were 42.9% (95% confidence interval [CI]1⁄441 to 45%) and 21.8% (95% CI1⁄419 to 26%), respectively. Five-year CSM rates were 34.0% (95% CI1⁄432 to 36) and 47.6% (95% CI1⁄444 to 52) for the same groups, respectively. In patients with organ-confined UCUB (T2N0), BPTtreated individuals had significantly increased risks of mortality (hazard ratio [HR]: 1.49, 95% CI1⁄41.04e2.13, P1⁄40.031) and CSM (HR: 1.66, 95% CI1⁄41.03e2.67, P1⁄40.036) compared to RC patients. Among those with non-organ confinedUCUB ( T3N0), no differencewas noted with respect to OS (HR: 1.22, 95%CI1⁄40.62e2.40, P1⁄40.571) and CSM (HR: 1.13, 95% CI1⁄40.48e2.64, P1⁄40.780) between the two groups. CONCLUSIONS: RC was associated with improved cancer control outcomes compared to BPT in organ-confined UCUB. However, no difference between the two treatment modalities was observed with respect to survival amongst patients with more advanced disease stage.