903P - Neuroendocrine carcinoma of the urinary bladder: A large analysis of the French GETUG consortium

Abstract

Background: Neuroendocrine carcinoma of the urinary bladder (NCUB) is a rare malignancy, accounting for <1% of bladder cancers. Despite high sensitivity to platinum-based chemotherapy (CT), prognosis remains poor. Methods: We retrospectively reviewed patients treated for NCUB in 18 French institutions to determine clinical/biologic characteristics, treatment efficacy and outcomes. Patient characteristics, treatment, follow-up and histological data were obtained from medical records. Tissue samples were pooled for further biological analyses. Results: From 1992 to 2017, we reviewed 234 NCUB cases (84% male, age 31–93 [median 67] years, ECOG PS 0–3 [median 1]). Small cell carcinoma was found in 47% of patients and large cell carcinoma in 9%; urothelial carcinoma was present in 51% of patients. Hematuria (71%) and pain (19%) were the main symptoms. Main metastatic sites at diagnosis of metastatic disease were lymph node (76%), liver (42%), bone (42%), pelvic recurrence (33%), lung (19%) or brain (12%). Of 230 patients evaluable for staging at diagnosis, 168 had stage I–III disease: stage I (3%), II (20%), III (34%), not evaluable (16%). They were treated with neoadjuvant CT (49%; mainly based on a platinum-based agent + etoposide [85%]), surgery (74%), radiotherapy (24%), and/or adjuvant CT (24%). Ninety-nine patients (59%) had metastatic recurrence. Median time to relapse was 4 months, disease-free survival was 14 months (95% confidence interval [CI] 12–18]), and median overall survival (mOS) was 28 months (95% CI 20–32). Of 62 patients (27%) with metastases at diagnosis, first-line CT was based on platinum + etoposide (81%), platinum + other drug (15%), or taxanes (4%). For these patients, median progression-free survival (mPFS) was 7 months (95% CI 4–9). Only 28 patients had second-line CT with mPFS of 5.2 months and mOS of 11 months (95% CI 8–15). Conclusions: This is, to our knowledge, the largest cohort of NCUB patients studied to date. Data emphasize the heterogeneity and aggressiveness of this disease. Future studies should investigate disease biology and the activity of targeted therapies in NCUB. Molecular characteristics based on tumor tissue analysis are underway. Legal entity responsible for the study: HEGP (European Georges Pompidou Hopsital). Funding: Pierre Fabre. Disclosure: All authors have declared no conflicts of interest.