Scientists Warn: Vaping Likely Causes Cancer

A sweeping scientific review is raising new concerns about the long-term health effects of vaping.

Nicotine-based e-cigarettes may pose a serious cancer risk, according to a major new review that challenges the long-standing perception of vaping as a safer alternative to smoking. The study, led by UNSW Sydney and published in Carcinogenesis, brings together evidence from human studies, animal experiments, and lab research to examine whether vaping itself can trigger cancer.

“To our knowledge, this review is the most definitive determination that those who vape are at increased risk of cancer compared to those who don’t,” Prof. Stewart says.

Unlike earlier research that focused on vaping as a pathway to traditional smoking, this analysis zeroes in on the devices themselves.

Researchers evaluated the chemical makeup of e-cigarette aerosols and found a mix of substances already known to damage DNA and disrupt normal cellular processes. These include volatile organic compounds and trace metals released during heating, both of which have been linked to cancer development.

“Considering all the findings – from clinical monitoring, animal studies and mechanistic data – e-cigarettes are likely to cause lung cancer and oral cancer,” Prof. Stewart says.

Although the results were consistent across different types of research, the exact number of cancer cases linked to vaping is still unknown.

“Our assessment is qualitative and does not involve a numerical estimate of cancer risk or burden. We’ll only be able to determine the precise risk once longer-term studies are available.”

Growing public health concerns

E-cigarettes first appeared in the early 2000s and reached Australia around 2008. They were initially marketed as a safer alternative to traditional cigarettes and as a tool to help people quit smoking.

Today, brightly colored and flavored devices are widely used, especially among young people. Vaping has become common in public spaces such as schools, bars, and train stations across Australia, despite new regulations introduced in 2023. Disposable and non-therapeutic vapes are banned, and therapeutic versions can only be sold in pharmacies for smoking cessation.

“E-cigarettes are known to be a gateway to smoking and hence cancer,” says co-author UNSW Associate Professor Freddy Sitas.

“But the extent to which they may cause cancer in their own right has not received as much attention in research,” he says.

“The evidence was remarkably consistent across fields,” he says. “It dictated an unequivocal finding now, though human studies that estimate the risk will take decades to accumulate.”

A clear outcome

Smoking has been studied for more than 100 years. Although e-cigarettes are relatively new, inhaling nicotine-containing aerosols has already been linked to addiction, poisoning, inhalation injuries, and burns.

Because long-term population data are not yet available, researchers rely on other types of evidence to assess cancer risk.

The team found many carcinogenic substances in e-cigarette aerosols, including volatile organic chemicals and metals released from heating coils.

They analyzed several lines of evidence: biomarkers in people that indicate DNA damage, oxidative stress, and tissue inflammation; mouse studies that produced lung tumors; and laboratory research showing cellular damage and disrupted biological pathways associated with cancer.

Taken together, the researchers say the findings consistently point in the same direction.

A compounding problem

There is also increasing evidence that many smokers who switch to vaping continue to use cigarettes.

“Most of those who use e-cigarettes to quit smoking end up in ‘dual-use-limbo’, unable to shake off either habit,” says A/Prof. Sitas.

“What we do know from recent epidemiological evidence from the USA is that those who both vape and smoke are at an additional four-fold increased risk of developing lung cancer.”

This was described in commentary also published by A/Prof. Sitas and Prof. Stewart in Cancer Epidemiology.

History repeating

A/Prof. Sitas and Prof. Stewart note similarities between early research on smoking and current concerns about vaping.

It took nearly a century of scientific study, from the mid-1800s to the landmark US Surgeon General’s report in 1964, before smoking was officially recognized as a cause of lung cancer.

During that time, early warning signs were often overlooked.

“Early reports linked smoking to infectious diseases such as tuberculosis, followed by cardiovascular disease, stroke and lung cancer,” A/Prof Sitas says.

He suggests a similar pattern may be emerging with vaping and warns against repeating past delays.

“E-cigarettes were introduced about 20 years ago. We should not wait another 80 years to decide what to do.”

References:

“The carcinogenicity of e-cigarettes: a qualitative risk assessment” by Bernard W Stewart, Henry Marshall, Billie Bonevski, Hayley J Griffin, Ashley M Hopkins, Malinda Itchins, Cassandra J Mazza, Natansh D Modi, Marissa Ryan, Megan Varlow and Freddy Sitas, 30 March 2026, Carcinogenesis.
DOI: 10.1093/carcin/bgag015

“Historical parallels between harms of tobacco and e-cigarettes” by Freddy Sitas and Bernard Stewart, 16 February 2026, Cancer Epidemiology.
DOI: 10.1016/j.canep.2025.102941

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