A comprehensive peer-reviewed review published June 21, 2026, in the journal Carcinogenesis has reached the most unambiguous conclusion to date about the cancer risk posed by e-cigarettes: nicotine-based vapes are likely to cause cancers of the lung and oral cavity.
The review was led by UNSW Sydney cancer researcher Adjunct Professor Bernard Stewart AM and included investigators from the University of Queensland, Flinders University, the University of Sydney, Royal North Shore Hospital, The Prince Charles Hospital, and Sunshine Coast University Hospital. The team brought together pharmacists, epidemiologists, thoracic surgeons, and public health researchers, a deliberate cross-disciplinary approach designed to evaluate the evidence from every scientific angle simultaneously.
"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," Professor Stewart stated. "Considering all the findings — from clinical monitoring, animal studies, and mechanistic data — e-cigarettes are likely to cause lung cancer and oral cancer."
The conclusion is significant not only for what it says but for how it was reached. Rather than waiting for decades of long-term epidemiological mortality data — the gold standard that took approximately 100 years to establish for cigarettes — the researchers synthesized over 100 studies spanning 2017 to 2025 across multiple scientific disciplines. Their argument is direct: the existing cross-disciplinary evidence is already sufficient to conclude that waiting for that long-term data would be a public health mistake.
What the Evidence Shows — and Who Is at Risk
The UNSW review drew on three categories of evidence: clinical findings in humans, animal experiments, and laboratory investigations of the chemical composition of e-cigarette aerosols.
On the animal side, one of the most striking findings came from a study by Tang and colleagues, cited in the review, in which mice exposed to e-cigarette aerosol for 54 weeks developed lung tumors at a dramatically higher rate than controls. Nine of 40 aerosol-exposed mice, 22.5%, developed lung adenocarcinomas; only 1 of 40 control mice developed a lung tumor. The aerosol exposure condition was designed to parallel human vaping behavior.
On the chemical side, research published in peer-reviewed journals has found that e-cigarette aerosols contain aldehydes including formaldehyde and acetaldehyde, volatile organic compounds, and heavy metals — all established carcinogens associated with DNA damage, oxidative stress, and chronic inflammation. A 2023 study found that exclusive vapers showed levels of DNA damage in oral epithelial cells comparable to cigarette smokers, with damage increasing based on frequency of use and flavor type.
At the human clinical level, published research has documented oxidative stress markers rising measurably after a single vaping session. The UNSW team noted the "consistency of findings across disciplines" as particularly striking, convergence across animal, mechanistic, and human clinical data that mirrors the early patterns seen in tobacco research decades before the full mortality picture emerged.
| Evidence Category | Key Finding |
| Animal studies | 22.5% of vaping-exposed mice developed lung adenocarcinomas vs. 2.5% of controls |
| Chemical analysis | Aerosols contain formaldehyde, acetaldehyde, heavy metals — known DNA-damaging agents |
| Human clinical data | DNA damage in oral cells of exclusive vapers comparable to smokers |
| Review scope | 100+ studies across 2017–2025 synthesized across multiple disciplines |
The Historical Parallel — and the Policy Argument
Professor Stewart and co-author Adjunct Associate Professor Freddy Sitas also published a companion piece in Cancer Epidemiology, drawing explicit historical parallels between vaping and tobacco. As Prism News reported, it took approximately 100 years of research to confirm that smoking causes lung cancer, with the landmark 1964 U.S. Surgeon General's report arriving only after decades of accumulating evidence, and another 50 years to calculate tobacco's full hazard profile.
The authors argue that repeating that delay for e-cigarettes, waiting for 20 to 40 years of mortality data before acting, would expose an entire generation of vapers to a preventable cancer risk that the current cross-disciplinary evidence already signals. This framing matters for U.S. regulators. The FDA's Center for Tobacco Products has authority over e-cigarettes, and ongoing Premarket Tobacco Application reviews continue to determine which products can legally remain on the U.S. market. The UNSW review does not call for any specific policy outcome, but its conclusion that the carcinogenic risk is already "likely" rather than speculative puts new pressure on existing regulatory frameworks.
In practical terms, this research is directly relevant to roughly 28 million American adults who the CDC estimates currently use e-cigarettes or have used them recently, many of whom began vaping under the belief that it was substantially safer than smoking. Professor Stewart acknowledged that exact case counts of attributable cancers remain 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." That caveat is important; it means the review does not claim to specify how many cancers vaping will cause. What it does claim, with the weight of over 100 studies, is that the causal direction is already clear.
What Vapers Should Know and What to Do
People who currently vape nicotine products should discuss their options with a physician, particularly if they have any history of respiratory symptoms, chronic cough, or unexplained mouth sores. Symptoms that warrant immediate medical attention include a persistent cough lasting more than three weeks, coughing up blood, unexplained shortness of breath, chest pain, or sores in the mouth that do not heal within two weeks.
The FDA's current guidance on e-cigarettes does not authorize any vaping product as a smoking cessation device. Approved FDA cessation aids include nicotine replacement therapies (patches, gum, lozenges), varenicline (Chantix), and bupropion (Wellbutrin). The National Cancer Institute's Smokefree.gov offers free quit plans, text coaching, and counseling referrals.
For parents, the data on youth vaping remains concerning. The UNSW researchers noted that e-cigarettes were first sold in the early 2000s and were marketed from the start as safer alternatives to combusted tobacco, marketing that reached a large population of teenagers and young adults who had no prior smoking history and who are now the first generation to have vaped for a decade or longer.
Frequently Asked Questions
Is vaping proven to cause cancer?
As of the June 21, 2026 UNSW Sydney review published in Carcinogenesis, researchers concluded that nicotine-based e-cigarettes are "likely" to cause lung and oral cancers based on convergent evidence from animal studies, human clinical data, and chemical analysis. The reviewers note that long-term mortality statistics comparable to those available for cigarettes do not yet exist, but argue the existing cross-disciplinary evidence already meets the threshold for a causal conclusion.
Which cancers are most associated with vaping?
The UNSW review specifically identified lung cancer and oral cavity cancer as the cancers for which current evidence most strongly supports a causal link to nicotine-based e-cigarette use.
Is vaping still safer than smoking?
The UNSW review was not designed to compare vaping and cigarettes head-to-head. Its central question was whether vaping causes cancer in its own right, and the answer was yes, likely. Comparing relative risk between the two products remains an active area of research, but the review's authors explicitly caution against assuming that "less harmful than cigarettes" means safe.
Who should be most concerned?
People who have vaped daily for multiple years, people who began vaping before age 25, when lung tissue is still maturing, and people who have any existing respiratory conditions or immune suppression face a potential elevated risk. Any person who vapes and has a persistent cough, mouth sores, or unexplained respiratory symptoms should speak with a physician.
What can people do to quit vaping?
FDA-approved cessation options include nicotine patches, gum, lozenges, varenicline, and bupropion. Smokefree.gov offers free text coaching and quit plans. Physicians can also prescribe combination therapy for patients with strong nicotine dependence.
