Association between Smoking and Overall and Specific Mortality in Patients with Bladder Cancer: A Population-based Study

Abstract

BACKGROUND: The role of smoking in the prognosis of bladder cancer may significantly impact clinical management. It is also a considerable burden to Taiwan’s economy and health of its citizens. OBJECTIVE: To search Taiwan’s National Health Insurance Research Database to determine whether smoking affected overall and cancer-specific mortality of patients with bladder cancer. METHODS: We collected data on basic information, tumor stage, and comorbidities. Each smoking case was propensity score-matched by age, sex, and diagnosis year to one control individual among bladder cancer patients. The study comprised a never-smoke and an ever-smoke group, with each group including 4,728 patients after matching. We evaluated the association between smoking and mortalities in patients with bladder cancer. Cox proportional regression modeling was used to estimate hazard ratios (HRs) of overall and cancer-specific mortality rates. Stratified analysis was also performed to estimate risk ratios of overall and cancer-specific mortalities in bladder cancer patients with and without a history of smoking history among different subgroups. RESULTS: The overall and specific mortality ratio of patients who were ever smokers were 1.15-fold and 1.16-fold, respectively, compared with those of never smokers (overall: 95% confidence interval [CI], 1.06–1.26, P = 0.0014; specific: 95% CI, 1.03–1. 03, P = 0.0176). Patients with bladder cancer who smoked and had significantly higher overall and specific mortality rates were those with Charlson Comorbidity Index (CCI)≥3 (overall: P = 0.0119; specific: P = 0.0092), diabetes mellitus (DM; overall: P = 0.0046; specific: P = 0.0419), and non-muscle-invasive bladder cancer (NMIBC; overall: P = 0.0038; specific: P = 0.0014). CONCLUSIONS: Overall and specific mortality rates were significantly higher in the ever-smoke group than in the never-smoke group. The ever-smoke group with male sex, CCI≥3, DM, and NMIBC had increased risks for overall and specific mortality.