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.