Although smoking has long been known to increase the risk of bladder cancer, the risk among smokers appears to have increased since the mid-1990s. This may be the result of changes in the composition of cigarettes or changes in inhalation patterns among smokers. These results were published in the Journal of the National Cancer Institute.
Although there is limited information about how the composition of cigarettes has changed over time, evidence suggests that the level of some carcinogens has increased. Furthermore, the introduction of low-nicotine cigarettes appears to have contributed to deeper and more frequent inhalation among smokers. As a result of these changes, smokers may now have a higher risk of bladder cancer than in the past.
To explore whether the risk of bladder cancer among smokers has increased over time, researchers evaluated information from studies conducted in New Hampshire during 1994-1998, 1998-2001, and 2001-2004.
- The link between smoking and bladder cancer appears to have grown stronger over time. Current smoking was linked with a threefold increase in risk during 1994-1998, a more than fourfold increase in risk during 1998-2001, and a 5.5-fold increase in risk during 2001-2004.
- Risk among former smokers was lower than risk among current smokers but also increased over time.
- The study also reported that for individuals with a similar total number of cigarettes smoked, smoking fewer cigarettes for a longer period of time appeared to pose a greater risk than smoking a greater number of cigarettes for a shorter period of time.
This study suggests that the risk of bladder cancer among smokers has increased over time. This may be the result of changes in the composition of cigarettes, changes in inhalation behavior among smokers, or both.
Reference: Baris D, Karagas MR, Verrill C et al. A case-control study of smoking and bladder cancer risk: emergent patterns over time. Journal of the National Cancer Institute. 2009;101:1553-1561.