A Single Institution Experience in the Management of Localized Neuroendocrine Carcinoma of the Bladder.

Background: Neuroendocrine carcinoma of the bladder (NEC-bladder) is a rare disease with poor outcomes and variable treatment approaches.

Materials And Methods: Patients with localized NEC-bladder treated with surgery or radiation between 2001-2021 were retrospectively identified. Rates of pathologic complete response (pCR) and downstaging were evaluated following NAC in surgically-treated patients. Progression-free survival (PFS) and overall survival (OS) were analyzed with univariable (log-rank) and multivariable (MVA; Cox regression) methods.

Results: Sixty-five patients were identified having a median age of 73. The tumor histology distribution was small cell (64.6%) or urothelial with NE differentiation (35.4%). Most patients (69.2%) received NAC. Patients received local therapy by surgery (78.5%) or chemoradiation (21.5%). The majority (62.7%) of surgical patients had ≥ pT2 with 37.3% having nodal involvement (pN+). The pCR and downstaging rates were 21.6% and 35.1%, respectively. At a median follow-up of 60 months (m), the median PFS and OS were 16.4m and 25.9m, respectively. NAC improved PFS (p=0.04) and downstaging improved PFS (p=0.012) and OS (p<0.001). Patients receiving NAC with ypN0 vs. ypN+ had median OS of 69.9m vs 15.3m, respectively (p<0.001). MVA identified receipt of NAC and pN as predictors of PFS; pN was predictive of OS. No differences in PFS or OS were seen between histology of primary tumor. The brain metastasis rate was 10.8% with all patients having small cell histology.

Conclusions: Optimized therapy in NEC-bladder includes NAC followed by local consolidation. Ascertainment of ypN0 is associated with long term survival, while pN+ remains associated with poor outcomes.