March 20, 2020

E-Cigarette Users Have Carcinogen Biomarkers Linked to Bladder Cancer in Urine

A study published in European Urology Oncology found that people who use e-cigarettes have substances in their urine that have a strong link to bladder cancer.

“Smoking is the number 1 modifiable behavioural risk factor for bladder cancer,” said Marc Bjurlin, MD, University of North Carolina Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina. “There is now evolving literature showing that people who vape may have similar carcinogens in their urine as combustible cigarette users. The first and foremost side effects that we’re seeing from electronic cigarette use are lung and pulmonary related. We won’t see the side effects for these other kinds of carcinogenic pathways until much later down the exposure pipeline.”

The researchers performed a systematic literature search of relevant articles published in peer-reviewed journals through January 2019 that reported on urinary biomarkers in e-cigarettes. Parent compounds and urinary biomarkers were classified according to the International Agency for Research on Cancer Monographs on the Evaluation of Carcinogenic Risks to Humans and cross referenced using the Collaborative on Health and the Environment, Toxicant and Disease Database to determine a link to bladder cancer, grouped by strength of evidence.

A total of 22 studies met final inclusion criteria and were included for analysis. In summation, these studies described 40 different parent compounds and 4 metals found in the urine of e-cigarette users. Since each parent compound can be metabolised several different ways, 63 unique toxicant or carcinogenic metabolite biomarkers were identified. Compared with nonuser controls, e-cigarette users had higher concentrations of urinary biomarkers of 6 carcinogenic compounds linked to bladder cancer.

“This finding shows us that people who vape will be exposed to a variety of different carcinogens,” said Dr. Bjurlin. “People who have decades of exposure to these carcinogens from vaping may be at risk for developing malignancies, especially bladder cancer.”

There were several limitations to the study, including that researchers did not know the levels of all of the cancer-causing substances in the urine of users from the studies. In addition, some studies included people who smoked both regular cigarettes and e-cigarettes. There were also cases when users smoked cigarettes and switched to e-cigarettes.

“The study population was quite heterogeneous, meaning that often studies looked at dual users, meaning those who used e-cigarettes and combustible cigarettes,” said Dr. Bjurlin. “That made it difficult to assess whether the carcinogen found in the urine was actually from the e-cigarette use or from the cigarette use.”

He said that more research is needed to determine the threshold of exposure to carcinogens that would lead to development of bladder cancer or other cancer types. He plans to lead a study that will evaluate carcinogens in the urine of e-cigarette users, smokers, and non-users.

“Although there is no definitive case yet linking bladder cancer to vaping, it may be reasonable to suspect that decades down the road after exposure to these byproducts, people who vape may be at risk of developing bladder cancer,” said Dr. Bjurlin.


SOURCE: UNC Lineberger Comprehensive Cancer Center
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