Outcomes In Bone Predominant (Bp) Urothelial Carcinoma (Uc).

441Background: The clinical phenotype of BP UC includes those patients (pts) with at least as many or more bone lesions than non-bone lesions. UC molecular subtypes that may correlate with prognosis have been defined. Better understanding of the clinical BP phenotype, which might correspond to the p53-like molecular subtype, is needed. Methods: We searched our biorepository to identify pts with metastatic UC. Electronic records of identified pts were reviewed and those with accessible records who received treatment at our institution were selected. Demographic, pathologic, treatment, response, progression-free and overall survival (PFS, OS) data were recorded. Imaging was reviewed to identify non-bone predominant (NBP) or BP disease based on imaging criteria. Results: 23 NBP and 9 BP pts, (59% men) were identified. Of BP pts, 44% had bone metastatic disease present at diagnosis (dx) vs. none of the NBP. Only 8% of NBP pts developed bone metastases during their course. The median number of lines of therapy...