Bladder cancer and e-cigarettes: Not a good combination

In patients with bladder cancer, the use of e-cigarettes may have several harmful associations, including the presence of carcinogenic compounds in the urine, and induction of DNA damage, while smoking in general may be associated with an increased mortality risk, according to three studies presented at the 112^th Annual Scientific Meeting of the American Urological Association (AUA).

"These studies raise new concerns about the harmful impact of e-cigarettes on bladder cancer," said Sam S. Chang, MD, MBA, professor of urologic surgery, Vanderbilt Ingram Cancer Center, Nashville, TN, who moderated the meeting session at which these studies were presented. "We've known traditional smoking raises bladder cancer risk, and given the surge in popularity of e-cigarettes, it's imperative we uncover any potential links to e-cigarette smoke and bladder cancer.”

Until now, little was known about the bladder cancer risks associated with e-cigarette use, a practice that has grown increasing popular over the past 10 years since its introduction.

Researchers, therefore, undertook these studies. The first was a population-based study in which researchers compared survival rates between over 14,000 smoking adults with bladder cancer who lived in Florida from 1981 to 2009. They found that smoking more packs per day was associated with an increased risk of mortality in patients with bladder cancer, and those smoking a minimum of 1 to 2 packs per day were significantly more likely to have a higher risk of mortality than those who smoked less than one pack per day. Finally, they found that even a slight reduction in the amount of smoking affected survival in these patients.

In the second study, researchers compared urine from e-cigarette users to that of non-smokers, and quantified the presence of five known bladder carcinogens present in both traditional cigarettes and in some e-cigarette liquids. They found that in 92% of e-cigarette users, the urine tested positive for two of the five carcinogenic compounds. Based on these results, these researchers plan to further study the effects of e-cigarettes on the development of bladder cancer.

In the third study, researchers from New York University, New York City, NY, assessed whether e-cigarette smoke induced DNA damage in bladder mucosa, and the effect of nicotine and its metabolites—nitrosamines and formaldehyde—on DNA repair and mutational susceptibility in cultured human urothelial cells.

They found that e-cigarette smoke induce tumorigenic DNA damage in bladder mucosa, and the nicotine, nitrosamine, and formaldehyde also induced the same type of DNA damage in human urothelial cells, inhibited DNA repair, and enhanced mutational susceptibility. In addition, they found that nicotine can be nitrosatized in urothelial cells, and then further metabolized into carcinogenic nitrosamines and formaldehyde.