Clinical characteristics and outcomes of nonurothelial cell carcinoma of the bladder: Results from the National Cancer Data Base

Objectives: To determine the clinical characteristics, treatment patterns, and outcomes of patients with nonurothelial cell bladder cancer (NUBC) in the United States. Methods: A total of 163,683 patients with bladder cancer from 1998 to 2014 in the National Cancer Data Base were identified. Of all, 153,262 had urothelial cell (UC) carcinoma (93.6%) and 10,421 had NUBC (6.4%) further classified as: squamous cell carcinoma (SC, 2.4%), adenocarcinoma (AC, 1.7%), neuroendocrine (NE, 1.3%), micropapillary (MP, a UC variant histology, 0.3%), lymphoid/haematopoietic (LH, 0.3%), and sarcoma/mesenchymal (SM, 0.3%). Analyses were run on the entire cohort, those with non-muscle-invasive disease (T0-1, N0, M0), muscle-invasive disease (MIBC, T2-4A, N0, M0), and metastatic disease (T4B or N+ or M+). Clinical characteristics and treatment received (surgery, chemotherapy, and radiation) were reported by histologic subtype. Survival analysis was performed via Kaplan-Meier estimates and Cox proportional hazards models. Results: Patients with NE, SC, MP, and AC were more likely to be diagnosed with metastatic disease (11.5% for UC vs. 40%, 31.3%, 17.8%, and 30.6%, respectively, P<0.001). Patients with NUBC were also more likely to have MIBC compared to UC (43% vs. 32.5%, respectively). For all patients, those with UC may be less likely to undergo cystectomy, chemotherapy, and radiation therapy (P<0.001). For all patients, NUBC, with the exception of LH, SM, and MP, was associated with inferior survival compared to UC (P<0.001). Conclusions: This encompassing clinical characterization and prognosis of NUBC patients in the United States shows NUBC patients have significantly different disease characteristics compared to those with UC, and present with more advanced disease, receive more treatment, and overall have inferior outcomes. Further work is needed to help improve outcomes for these patients.