A Study on Cigarette Smoking and Bladder Cancer

About the Study

Cigarette smoking causes cancer in at least 15 different parts of the body, including the bladder. Smoking causes roughly half of all bladder cancers in both men and women in the United States, making it the leading preventable risk factor, far ahead of workplace exposure to industrial chemicals. The higher the risk, the more you smoke. The risk of bladder cancer increases with smoking duration (the number of years you have smoked) and intensity (the number of cigarettes smoked per day), with duration having a greater effect. Overall, smokers are at least three times more likely to develop bladder cancer than non-smokers.

An analysis of data from multiple previously published studies (known as a meta-analysis) discovered that current smokers had a 3.5 times higher risk of bladder cancer than non-smokers, with former smokers having a 2 times higher risk. A second meta-analysis discovered a similar increase in bladder cancer risk for both male and female smokers, but a higher risk in European populations compared to Asian populations. Some genetic variants have also been linked to an increased risk of bladder cancer in smokers.

Second Hand Smoke (SHS), also known as involuntary smoking, exposes children, pets, and nonsmokers to the same carcinogens that smokers inhale. There is no safe level, but home and workplace exposure are particularly concerning, with nonsmokers exposed to SHS in these settings having a 20-30% increased risk of lung cancer. While more research is needed to confirm potential links to other cancers, and bladder cancer results have been inconsistent, a meta-analysis of 14 studies found that second-hand smoke exposure was associated with a 22% increase in bladder cancer risk.

This is less than the risk increase depicted in the graph. Although the precise level of risk is unknown, it is reasonable to conclude that SHS significantly increases the risk of developing bladder cancer. Blood levels of cotinine, a chemical formed in the body after nicotine exposure, can be used to assess SHS exposure. In relation to this, encouraging findings from the National Health and Nutrition Examination Survey (NHANES) show that the percentage of nonsmokers exposed to SHS decreased from 88% in 1988 to 25% in 2014, but approximately two out of every five children were still exposed to SHS's harmful effects. Pets are also at risk! Smokers' dogs, cats, and birds are more likely to develop cancer.

Though a variety of factors may have influenced by the decision to begin and continue smoking, quitting is a personal choice; each must want to quit. Many people find that it takes several attempts before they succeed, as evidenced by the declining rates of smoking in the United States. Notably, quit rates improve with peer support and specialized medication, so it's worth experimenting with different approaches to see what works best for you. Nicotine replacement therapy (e.g., patches, gum, and lozenges) and two prescription medications, varenicline and bupropion, are FDA-approved smoking cessation medications.

It is important to note that the FDA has not approved e-cigarettes (vaping) for smoking cessation. Randomized trials show that vaping with nicotine-containing e-cigarettes increases quit rates when compared to nicotine replacement therapy. However, it is unknown whether people will continue to vape or successfully quit smoking.