TOBACCO-SMOKE INHALATION PATTERN, TOBACCO TYPE, AND BLADDER-CANCER IN SPAIN

The association between tobacco smoking and bladder cancer was investigated in a multicenter case-control study conducted in five provinces of Spain between 1983 and 1986. A matched analysis was carried out in males, based on 430 histologically confirmed cases, 405 hospital controls, and 386 population controls, matched by age and place of residence. An increased risk was found for smokers as compared with nonsmokers (odds ratio (OR) = 3.79, 95% confidence interval (CI) 2.41-5.97), and this increase was significantly associated with the intensity of smoking. Smokers of filter-tipped cigarettes had a reduced risk as compared with smokers of non-filter-tipped cigarettes (OR = 0.57, 95% CI 0.32-1.02). A diminution of risk was also observed for smokers of low-tar and low-nicotine ("light") cigarettes. Depth of inhalation was strongly associated with illness. No difference was shown in the logistic regression model between smokers of black tobacco and smokers of blond tobacco after controlling for depth of inhalation. Although the number of persons who smoked blond tobacco exclusively was small, the results suggest that it is important to consider inhalation patterns when studying risk variations between smokers of black tobacco and smokers of blond tobacco. The age at which a person started to smoke did not appear to affect risk. An analysis of the decrease in risk associated with years since quitting smoking suggested that different components of cigarette smoke may play a role at different stages of the carcinogenic process.