Effects of timing and type of tobacco in cigarette-induced bladder cancer.

We analyzed a case-control study of bladder cancer in Torino (512 male and 55 female cases; 596 male and 202 female controls) with emphasis on the timing of cigarette smoking and the use of black or blond tobacco. The risk of bladder cancer was 2 to 3 times higher among smokers of black tobacco than among smokers of blond tobacco. Both groups of smokers showed a beneficial effect of smoking cessation, with an immediate decline in risk. This pattern is consistent with a late-stage effect of smoking. Among smokers of black tobacco, there was a gradient of risk with early exposure, and smokers who had quit never showed a drop to base-line levels of risk. These patterns, not apparent in users of blond tobacco, suggest an early stage effect of black tobacco, perhaps due to the higher concentration of aromatic amines in black than blond tobacco smoke and the higher blood levels of the hemoglobin adduct with 4-aminobiphenyl (a human bladder carcinogen) among smokers of black tobacco.