A California Cancer Registry Analysis of Urothelial and Non-urothelial Bladder Cancer Subtypes: Epidemiology, Treatment, and Survival.

Introduction: We evaluated epidemiologic trends and survival for bladder cancer histologic subtypes in California patients by comparing urothelial carcinoma of the bladder (UCB) and non-urothelial subtypes including squamous cell carcinoma (SCC), adenocarcinoma (ADC), and small-cell carcinoma (SmCC).

Materials And Methods: The California Cancer Registry (CCR) was queried for incident bladder cancer cases from 1988 to 2012. Epidemiologic trends based on tumor histology were described. The primary outcome was disease-specific survival (DSS). Kaplan-Meier and multivariable Cox regression survival analyses were performed.

Results: A total of 72,452 bladder cancer cases (66,260 UCB, 1390 SCC, 587 ADC, 370 SmCC, and 3845 other) were included. The median age was 72 years (range, 18-109 years). ADC was more common in younger patients. Male:female ratios varied among cancer types (3.1:1 in UCB, 2.9:1 in SmCC, 1.6:1 in ADC, and 0.9:1 in SCC). Most non-urothelial cases (> 60%) presented at advanced stages, whereas most UCB cases (80.6%) were localized. Kaplan-Meier analysis revealed the best 5-year DSS and overall survival (OS) in UCB, whereas the worst outcomes were seen with SCC and SmCC (P < .0001). Multivariable analysis controlling for age, gender, tumor stage, and grade demonstrated that non-urothelial histologic subtypes were associated with significantly worse DSS compared with UCB (SCC hazard ratio [HR], 2.612; SmCC HR, 1.641; and ADC HR, 1.459; P < .0001).

Conclusions: Non-urothelial bladder cancers have worse oncologic outcomes than UCB in California patients. SCC and SmCC are associated with the worst DSS based on univariable and multivariable analyses.