Mortality difference by Gender and Race in Squamous Cell Cancer of the Bladder

Abstract

Introduction. Squamous cell carcinoma (SCC) of the bladder is a rare form of bladder cancer with unique clinical features. Prior studies have shown that gender and race influence survival following the diagnosis of bladder cancer, but no study has assessed the importance of these factors in SCC alone. We used a large, population-based cancer registry to assess the effect of gender and race on survival following the diagnosis of SCC of the bladder and indentify factors that may modify this effect. Materials and Methods. Cases of SCC of the bladder were identified from all registries available through the Surveillance, Epidimiology, and End Result (SEER) cancer registry from 1988 to 2008. In addition to cancer location and histology, data were collected on race and gender, as well as covariates such as age, treatment received, stage, and grade. Survival differences were assessed using Kaplan-Meier curves, log-rank testing, and cox-proportional hazards modeling. Results. We identified 1,969 cases of SCC for analysis. The cohort was 49.5% female and 85.5% white. Stage and grade were found to modify the effect of gender on survival and the results for gender were stratified by these variables. Women with low-grade, low-stage disease had a 2.87 higher risk of death than their male counterparts (95% CI HR 1.27-6.47, p=0.011) while a significant difference was not found for other stages or grades. Women with localized disease and node-positive disease were also at higher risk of death (HR 1.20, CI 1.04-1.39, p=0.011 and HR 1.40, 95% CI 1.01-1.95, p=0.041, respectively). Finally, black men had a significantly increased risk of death over white men (HR 1.35, 95% CI 1.04-1.76, p=0.026) while black women had a non-significantly increased risk of death over white women (HR 1.16, 95% CI 0.92-1.47). Conclusions. These results show gender and race are significant predictors of survival following the diagnosis of SCC of the bladder. These differences exist after stratifying by disease stage, grade, and primary treatment. Unmeasured factors related to either disease pathology or treatment may account for this survival difference.