875P - Outcomes of patients with metastatic urothelial carcinoma (mUC) with exclusive bone metastases: Focus on a special patient population

Abstract

Background: Patients (pts) with aUC with exclusive bone metastatic spread represent a rare subgroup of pts with unique clinical features. These pts deserve special consideration, as they are usually excluded from clinical trials due to the lack of measurable disease according to RECIST criteria. We focused on their access to treatment and outcomes in a retrospective study. Methods: Cases were extracted from the pool of 1,911 pts with a diagnosis of mUC from the RISC database (db). Data from 23 centers was collected. Results of 1st-line, platinum-based chemotherapy in bone-only pts were compared with those from the remaining pts in the RISC db. Summary statistics were used to describe pt characteristics and outcomes. Kaplan-Meier method was used to estimate time to event outcomes such as progression-free survival (PFS) and overall survival (OS). Both OS and PFS are measured from the date of diagnosis of metastatic disease. Univariable and multivariable Cox analyses were performed. All tests were two-sided and statistical significance was defined as a p-value ≤0.05. Results: A total of 128 evaluable pts (6.7%), treated between 02/1997 and 04/2013, were identified. ECOG-PS was ≥1 in 85.9% vs. 66.3% of the remaining pts from RISC db. 73 (57%) received 1st-line chemotherapy, that was platinum-based in all pts, and 28 of them (38.4%) 2nd-line CT (vs. 75.8% and 42.5%, respectively, from the RISC db). On multivariable analyses, only the chemotherapy administration was significantly associated with improved OS among bone-only mUC pts (p < 0.001). Among platinum-treated pts (total evaluable N = 972), significantly-different PFS and OS estimates were observed according to the bone metastases status (no bone metastases vs. bone metastases only vs. bone + other, p < 0.001). 2-year PFS was: 37.4%, 28.8%, 25.9%. 2-year OS was: 35.5%, 15.8%, 23.0%, among the above subgroups, respectively. Conclusions: Pts with bone only metastases are less likely to receive systemic therapy than pts with metastases to other sites, likely due to lower PS. The prognostic impact of having exclusive bone metastases or additional sites seems to be equally poor. Clinical trials with new agents should focus on this population. Legal entity responsible for the study: Andrea Necchi Funding: None Disclosure: All authors have declared no conflicts of interest.