Abstract
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). 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. 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). 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.
Highlights
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)
Multivariable analysis controlling for age, gender, tumor stage, and grade demonstrated that non-urothelial histologic subtypes were associated with significantly worse disease-specific survival (DSS) compared with UCB (SCC hazard ratio [HR], 2.612; SmCC HR, 1.641; and ADC HR, 1.459; P < .0001)
We found that 8.6% of cases in the Cancer Registry (CCR) were non-urothelial subtypes, which is consistent with the estimated national rate of 10%
Summary
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). Bladder cancer comprises 81,190 cancer cases and 17,240 deaths per year in the United States.[1] Of the bladder cancer histopathologic subtypes, urothelial carcinoma (UCB) is responsible for greater than 90% of cases.[2] Non-urothelial types include squamous cell carcinoma (SCC) (2%), adenocarcinoma (ADC) (1%), and small-cell carcinoma (SmCC) (0.5%1%).[3,4] In Western countries, the pathophysiology of SCC is related to chronic bladder inflammation and irritation, such as that associated with indwelling urinary catheters.[5] SCC was historically the leading form of bladder cancer in regions such as the Middle East and North Africa owing to endemic schistosomiasis, but the incidence has decreased owing to anti-bilharzial treatments and snail control.[6] ADC is more common in regions with schistosomiasis, and it is associated with patients with bladder exstrophy.[3] SmCC is an uncommon neuroendocrine tumor resembling small-cell carcinoma of the lung. It typically presents in older Caucasian males and is associated with dismal survival outcomes compared with UCB.[7]
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