MP26-15 MOLECULAR SUBTYPING REVEALS LUMINAL BLADDER TUMORS HAVE LOWER RATES OF PATHOLOGICAL UPSTAGING AT RADICAL CYSTECTOMY

INTRODUCTION AND OBJECTIVES:Upstaging of bladder cancer from precystectomy clinical stage ≤T2 to non-organ confined pathologic stage ≥T3 or N+ at radical cystectomy (RC) is common and can significantly increase the risk of cancer-specific mortality (CSM). We assessed the ability of a genomic subtyping classifier (GSC) to predict pathological upstaging in a multi-institutional cohort of patients with clinical T1-T2 bladder cancer treated with RC.METHODS:A cohort of 206 patients with clinical high-grade, organ-confined (cT1-T2, N0M0) treated with RC and bilateral PLND without neoadjuvant chemotherapy (NAC) was selected from the registries of 7 academic hospitals. Precystectomy bladder tumor transurethral resection FFPE specimens were submitted for genomic testing with the Decipher Bladder assay (GenomeDx, San Diego, CA). Uni- and multi-variable logistic regression analysis (UVA/MVA) were used to evaluate a locked GSC for upstaging, defined as pT3/T4 and/or pTanyN1-3 disease at RC. Cumulative incidence of CS...