Smoking and bladder cancer in Spain: effects of tobacco type, timing, environmental tobacco smoke, and gender

Abstract

We examined the effects of dose, type of tobacco, cessation, inhalation, and environmental tobacco smoke exposure on bladder cancer risk among 1,219 patients with newly diagnosed bladder cancer and 1,271 controls recruited from 18 hospitals in Spain. We used unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for the association between bladder cancer risk and various characteristics of cigarette smoking. Current smokers (men: OR, 7.4; 95% CI, 5.3-10.4; women: OR, 5.1; 95% CI, 1.6-16.4) and former smokers (men: OR, 3.8; 95% CI, 2.8-5.3; women: OR, 1.8; 95% CI, 0.5-7.2) had significantly increased risks of bladder cancer compared with nonsmokers. We observed a significant positive trend in risk with increasing duration and amount smoked. After adjustment for duration, risk was only 40% higher in smokers of black tobacco than that in smokers of blond tobacco (OR, 1.4; 95% CI, 0.98-2.0). Compared with risk in current smokers, a significant inverse trend in risk with increasing time since quitting smoking blond tobacco was observed (> or =20 years cessation: OR, 0.2; 95% CI, 0.1-0.9). No trend in risk with cessation of smoking black tobacco was apparent. Compared with men who inhaled into the mouth, risk increased for men who inhaled into the throat (OR, 1.7; 95% CI, 1.1-2.6) and chest (OR, 1.5; 95% CI, 1.1-2.1). Cumulative occupational exposure to environmental tobacco smoke seemed to confer increased risk among female nonsmokers but not among male nonsmokers. After eliminating the effect of cigarette smoking on bladder cancer risk in our study population, the male-to-female incidence ratio decreased from 8.2 to 1.7, suggesting that nearly the entire male excess of bladder cancer observed in Spain is explained by cigarette smoking rather than occupational/environmental exposures to other bladder carcinogens.