Introduction

Tobacco smoking is recognized as the most established risk factor for bladder cancer. As such, we aimed to assess the ecological association between tobacco smoking prevalence and bladder cancer incidence in the US over the past half-century, and to contrast it with that observed for lung cancer, which represents the most established tobacco-related malignancy.

Methods

The annual overall tobacco smoking prevalence rates were extracted from the Report of the Surgeon General (1950-1978) and the Center for Disease Control website for the years 1953-1983. The overall age-adjusted incidence rates of bladder and lung cancers were derived from the Surveillance, Epidemiology, and End Results database for the years 1983-2013 (30-year time-lag). All analyses were stratified according to gender. Weighted least square regression models were used to assess the bladder and lung cancer incidence rate differences (IRD) and the proportion of changes in incidence of each malignancy related to tobacco smoking prevalence variations. Additional comparisons between the associations of tobacco smoking prevalence with bladder vs. lung cancer incidence rates were performed using a Wald test.

Results

The associations between tobacco smoking prevalence and bladder cancer incidence were not significant in the overall (IRD=+0.04; 95%CI: from -0.14 to +0.22; P=0.631), men (IRD=+0.07; 95%CI: from-0.09 to +0.23; P=0.374) and women (IRD=+0.12; 95%CI: from -0.01 to +0.25; P=0.061) populations. In contrast, the associations between tobacco smoking prevalence and lung cancer incidence were significant in the overall (IRD=+3.55; 95%CI: from +3.09 to +4.00; P<0.001), men (IRD=+4.82; 95%CI: from +4.44 to +5.20; P<0.001) and women (IRD=+3.55; 95%CI: from +3.12 to +3.99; P<0.001) populations. The difference between the observed associations of tobacco smoking prevalence with bladder vs. lung cancer incidence was significant in all examined populations (all P<0.001). Tobacco exposure accounted for an estimated 0.81%, 2.74% and 11.59% of the variation in bladder cancer incidence vs. 89.72%, 95.80% and 90.69% of the variation in lung cancer incidence in the overall, men and women populations, respectively.

Conclusions

In contrast to lung cancer, our study showed that variations in tobacco smoking prevalence were not associated with the incidence trends of bladder cancer in the US population over the past half-century._x000D_

Funding

none