A comprehensive review led by UNSW Sydney cancer researchers concludes that nicotine-based e-cigarettes are likely to cause cancers of the lung and oral cavity, drawing on evidence from human biomarkers, animal studies and laboratory research. The authors say long-term studies are still needed to quantify the level of risk in people who vape.
The review, published in the journal Carcinogenesis, assessed evidence from clinical monitoring of people who vape, experiments in animals and mechanistic laboratory studies.
Lead author Adjunct Professor Bernard Stewart of UNSW Sydney said the authors viewed the work as the strongest synthesis to date pointing to elevated cancer risk in people who vape compared with non-users.
“Considering all the findings – from clinical monitoring, animal studies and mechanistic data – e-cigarettes are likely to cause lung cancer and oral cancer,” Stewart said.
According to the authors, e-cigarette aerosols can contain carcinogenic compounds, including volatile organic chemicals and metals that can be released from heating coils. The review highlighted findings from biomarker studies indicating DNA damage, oxidative stress and inflammation, alongside animal studies reporting lung tumours after exposure, and laboratory work showing cellular damage and disrupted biological pathways linked to cancer.
The researchers cautioned that the review does not provide a numerical estimate of cancer risk or a projection of how many cancer cases vaping might cause, arguing that precise risk estimates will depend on longer-term human studies.
The authors also pointed to concerns about “dual use,” in which smokers take up vaping but continue to smoke. Co-author Associate Professor Freddy Sitas said recent epidemiological evidence from the United States suggests that people who both vape and smoke face an additional roughly four-fold increased risk of developing lung cancer, beyond the already high risk associated with smoking.
The team compared today’s debate about vaping with the early history of research on cigarettes, noting that it took decades of study—culminating in the U.S. Surgeon General’s 1964 report—before smoking was officially recognised as a cause of lung cancer.
E-cigarettes were first sold in the early 2000s and became available in Australia around 2008, the researchers said.
