Potential link between e-cigarettes and bladder cancer risk needs further study
Catherine Amey, Senior Medical Writer, Touch Medical Media, Goring-On-Thames, UK

“Vaping” has increased rapidly in popularity since its introduction over a decade ago yet the safety profile remains to be well characterized. Two studies presented at the 12th Annual Scientific Meeting of the American Urological Association (AUA) raise concern for e-cigarette smokers and bladder cancer risk.1,2

In a study comparing urine samples from 13 e-cigarette users and 10 non-smoking control subjects who did not use e-cigarettes, 12 of e-cigarette users had the carcinogenic compounds, 2-naphtylamine and 0-toluidine, present in their urine.1

In a separate study, researchers examined the effect of nicotine and its metabolites, nitrosamines and formaldehyde, on DNA repair and mutational susceptibility in cultured human urothelial cells. They found:
1. E-cigarette smoke induced tumorigenic DNA damage in the bladder mucosa
2. Nicotine can be nitrosatized in urothelial cells and then metabolized further into carcinogenic nitrosamines and formaldehyde
3. Nicotine and the metabolites nitrosamine and formaldehyde induced tumorigenic DNA damage in the bladder mucosa
4. Nicotine, nitrosamine and formaldehyde inhibited DNA repair and enhanced mutational susceptibility.

These findings led the investigators to predict that e-cigarette smokers may have a higher risk of bladder cancer than non-e-cigarette users.

"These studies raise new concerns about the harmful impact of e-cigarettes on bladder cancer," said Dr Chang, professor of urologic surgery at Vanderbilt Ingram Cancer Center, who moderated the press conference where these data were presented, at the Boston Convention and Exhibition Centre on May 15, 2017. "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.”

“This research underscores the importance of smoking cessation (of both traditional and e-cigarettes) for people with bladder cancer, and people looking to avoid it."

Data on the long-term safety of e-cigarettes will be crucial to develop guidelines and regulatory decisions on e-cigarettes. The ongoing 5-year, multicentric, prospective study on the long-term efficacy and safety (in terms of smoking-related serious diseases requiring hospitalization) of e-cigarette smoking will also include self-reported adverse events as a secondary outcome measure. The results of this study may therefore throw light on the safety profile of e-cigarettes.3-5

REFERENCES


1. Fuller T, Acharya A, Bhaskar G, et al., MP88-14. Evaluation of e-cigarettes users urine for known bladder carcinogens,The Journal of Urology, 2017;197:e1179.
2. Lee HW, Park SH, Weng MW, et al., PNFBA-11 E-cigarette smoke is potentially bladder carcinogenic – it induces tumorigenic dna adducts and inhibits dna repair in urothelial cells,The Journal of Urology, 2017;197 e913.
3. Manzoli L, La Vecchia C, Flacco ME, et al., Multicentric cohort study on the long-term efficacy and safety of electronic cigarettes: study design and methodology,BMC Public Health, 2013;13:883.
4. Manzoli L, Flacco ME, Ferrante M, et al., Cohort study of electronic cigarette use: effectiveness and safety at 24 months, Tob Control, 2017;26:284-92.
5. Manzoli L, Flacco ME, Fiore M, et al., Electronic Cigarettes Efficacy and Safety at 12 Months: Cohort Study, PLoS One, 2015;10:e0129443.