Australian cancer researchers have concluded that nicotine-based e-cigarettes are likely to cause lung and oral cancer, in what they describe as the most definitive assessment of vaping’s carcinogenic potential to date.
The study, published in the peer-reviewed journal Carcinogenesis and led by the University of New South Wales (UNSW), examined a massive longitudinal span of evidence from 2017 to 2025.
By synthesising clinical studies, animal experiments, and laboratory research, the team identified a “remarkable consistency” of risk across all biological levels.
A Cocktail of Carcinogens
The research team identified specific carcinogenic compounds within e-cigarette aerosols that go beyond simple nicotine delivery. Key findings include:
- Identification of volatile organic chemicals and toxic metals leached from heating coils
- Evidence of DNA damage, oxidative stress, and tissue inflammation
- Documented lung tumour formation in animal studies and interruption of cell signalling in laboratory environments
“Considering all the findings—from clinical monitoring to mechanistic data—e-cigarettes are likely to cause lung cancer and oral cancer,” lead author Adjunct Professor Bernard Stewart, a cancer researcher from UNSW’s Paediatrics and Child Health discipline, said in a press release.
“There is no doubt that the cells and tissues of the oral cavity, the mouth and the lungs are altered by inhalation from e-cigarettes.”
The ‘Dual-Use’ Trap
The study also highlights a dangerous trend in public behaviour. Co-author Freddy Sitas, an epidemiologist at UNSW, pointed to the “dual-use limbo” where smokers take up vaping to quit but end up doing both.
A 2024 study cited by the researchers suggests that smoking and vaping together increases the risk of lung cancer fourfold compared to smoking alone.
“Unless there is a proven device to stop people from vaping, then we’re stuck in this high-risk population that starts using both,” Sitas said. “Those people are at much higher risk of getting lung cancer than just smoking alone.”
Debate Over Clinical Implications
Not all experts believe the findings should reshape clinical practice.
Professor Nick Zwar, Chair of the Royal Australian College of General Practitioners (RACGP’s) Smoking Cessation Guidelines Expert Advisory Group, acknowledged the research as solid but cautioned against overreaction.
“I don’t think it changes the message that nicotine vaping is a reasonable therapeutic option when people haven’t succeeded with other methods,” he told newsGP.
The RACGP’s existing smoking cessation guidelines (pdf) maintains vaping as a “last-line” option, used only when behavioural support and traditional nicotine replacement therapies have failed.
Zwar said abandoning vaping risks discarding a useful tool for a population already facing serious harm from tobacco. He said a short-term switch to vaping—perhaps three to six months—may still be clinically defensible.
“It’s an argument for prospective studies, because I’m sure it’s not going to be completely safe—no one thinks it is,” he said.
A Warning From History
The UNSW team warns that action should be taken early to prevent a repeat of history seen in the tobacco industry in the 2oth century.
From as bar back as the 1920s, studies found associations between lung cancer and smoking, which were confirmed during the 1940s and 1950s.
However, it was not until 1964 when the U.S. Surgeon General issued a landmark report that smoking was officially recognised as a cause of lung cancer.
The report found “cigarette smoking is causally related to lung cancer in men … The data for women, though less extensive, point in the same direction.”
“Cigarette smoking contributes substantially to mortality from certain specific diseases and to the overall death rate,” the report concludes.
The researchers said the same pattern is now unfolding with vaping, and that the medical community cannot afford to repeat the lethal delay.
“The direction we intend is primarily to influence regulators, to give them further clarity in the need to control what has been described as a youth epidemic,” Stewart said.
“E-cigarettes were introduced about 20 years ago. We should not wait another 80 years to decide what to do,” Sitas said.
“The evidence was remarkably consistent across fields. It dictated an unequivocal finding now, though human studies that estimate the risk will take decades to accumulate.”
The study, which aims to provide regulators with clearer grounds for action, was a collaborative effort including pharmacists, epidemiologists, thoracic surgeons, and public health researchers from the University of Queensland, Flinders University, the University of Sydney, and several major hospitals.