Bladder cancer and black tobacco cigarette smoking. Some results from a French case-control study

A retrospective study was planned in the Hérault (Mediterranean) region of France where bladder cancer mortality and incidence rates are high. In the present paper, variations in bladder cancer risk according to various smoking-related variables, in particular time of exposure and type of tobacco, are examined. This case-control study with 219 male incident cases and 794 male population controls randomized from electoral rolls was carried out in 1987-89. Trained interviewers obtained information on demographics, dietary habits (coffee, alcohol, artificial sweeteners, vegetables, spices, etc.), occupational exposures and detailed history of tobacco smoking (average number of cigarettes per day, number of years of smoking, age at which they began and/or quitted smoking, use of filter-tip and type of tobacco). The odds ratio (OR) for cigarette smokers versus non-smokers was greater than 5. Results for number of cigarettes daily, duration of smoking and lifetime smoking showed a highly significant dose-response relationship, which was confirmed when these variables were treated as continuous in a logistic regression model. Eighty-eight percent of the smokers used black tobacco. Quitting smoking did not result in a significant reduction in bladder cancer risk. Higher risks were associated with starting to smoke at an early age (OR before age 13 versus after age 21 = 3.42; 95% CI 1.07-10.9) and with black tobacco smoking (OR black versus blond = 1.63; 95% CI 0.73-3.64). Results suggest that black tobacco may be more harmful than blond tobacco and may have an early non-reversible role in bladder carcinogenesis.