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

By Lisa Rapaport

March 26, 2020

(Reuters Health) - Biomarkers of carcinogens with a strong link to bladder cancer are present in urine of e-cigarette users, a systematic review suggests.

As reported in European Urology Oncology, researchers pooled data from 22 studies that analyzed the urine of people who used e-cigarettes or other tobacco products for evidence of cancer-linked compounds or biomarkers of those compounds. They found 40 different parent compounds that can be processed in the body to produce 63 different toxic chemicals or carcinogenic metabolites.

Six of those chemicals have a strong link to bladder cancer, according to the researchers' analysis of carcinogen databases of the International Agency for Research on Cancer and the Collaborative on Health and the Environment Toxicant and Disease Database.

They found evidence in some studies that e-cigarette users had significantly higher levels of several carcinogens that can be metabolized into substances linked to bladder cancer in their urine compared to people who had never used them.

"Although the malignant potential of e-cigarettes on bladder cancer remains unknown and is likely less than that of combustible cigarettes, the mere presence of these urinary carcinogens strongly associated with bladder cancer is highly concerning," said lead author Marc A. Bjurlin of the Lineberger Comprehensive Cancer Center at the University of North Carolina at Chapel Hill.

"The ongoing popularity of e-cigarettes and the continued evolution in e-cigarette-like devices requires a careful evaluation of the present evidence and honest discussions with patients about possible benefits and risks to consider, including the potential for bladder cancer," Bjurlin said by email.

While public health agencies including the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention have warned that there are health risks of vaping, including for e-cigarette-associated lung injury, their safety profile has not been definitively characterized, Bjurlin and colleagues write in European Urology Oncology.

Some carcinogens inhaled with e-cigarette use are filtered in the lungs and the rest pass into the bloodstream, Bjurlin said. The kidneys then filter some of the carcinogens in the blood and the remainder are excreted into the urine.

Different vaping devices allows the user to heat e-liquids to higher temperatures, which may produce more carcinogens, while different e-liquids contain varying amounts of nicotine, flavorings, and other chemicals which also may influence the type of carcinogen produced, Bjurlin added.

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 both vaped and used traditional cigarettes. There were also cases when users smoked cigarettes and switched to e-cigarettes.

More research is still needed to determine the potential cancer risks associated with vaping, said Irfan Rahman, a professor of environmental medicine, pulmonary medicine, and public health sciences at the University of Rochester Medical Center in New York.

"Vaping produces various aldehydes and organic polyaromatic hydrocarbons (PAH) like diesel exhaust that can be metabolized in lungs, liver, and kidney and excreted in urine," Rahman, who wasn't involved in the study, said by email.

"Any e-liquid or e-cigarette pods can generate PAH upon thermal breakdown of chemicals by vaping, which can be detected in aerosol," Rahman said.

SOURCE: https://bit.ly/2UzwLqg European Urology Oncology, published online March 16, 2020.