A comprehensive scientific review published in the journal Carcinogenesis has concluded that nicotine-based e-cigarettes are “probably carcinogenic to humans.” This landmark finding directly challenges the long-held narrative that vaping is a safe alternative to traditional smoking, linking the practice to lung and oral cancers.
Led by renowned cancer researcher Bernard Stewart from the University of New South Wales, the study analyzed peer-reviewed experimental data published between 2017 and 2025. The research team synthesized clinical data, animal bioassays, and laboratory mechanistic experiments to evaluate the long-term health impacts of vaping.
Unequivocal Pre-Cancerous Changes
The review concluded that e-cigarette aerosols exhibit all 10 key characteristics of recognized carcinogens. According to the researchers, vaping consistently triggers several harmful biological responses in the human body:
- Direct DNA damage and oxidative stress
- Epigenetic modifications in cells
- Chronic inflammation in both the oral cavity and the lungs
“There is no doubt that cells and tissues in the oral cavity, mouth, and lungs are altered by inhaling e-cigarettes,” Stewart stated, describing the biological changes as “unequivocal” evidence of pre-cancerous transformation.
This cellular damage was mirrored in animal trials cited in the review. Specifically, 22.5% of mice exposed to e-cigarette aerosols for 54 weeks developed lung adenocarcinomas, compared to just a single tumor observed in the control group.
The High Risk of Dual Use
One of the study’s most alarming findings involves “dual users”—individuals who both vape and smoke traditional cigarettes. Many smokers transition to vaping but end up caught in an “in-between” state of dual use rather than quitting entirely.
According to a cited 2024 case-control study by Ohio State University, dual users faced an adjusted odds ratio of 38.7 for developing lung cancer compared to non-smokers. This represents approximately four times the risk of smoking tobacco alone. Co-author Freddy Sitas warned that this common pattern of behavior exposes users to significantly compounded health hazards.
A Call for Precaution Amid Controversy
In an accompanying editorial in Cancer Epidemiology, Stewart and Sitas advocated for a strict precautionary approach. They argued that while the tobacco industry historically exploited scientific uncertainty to delay regulation, policy-makers should not grant vaping the same leniency given the strength of current carcinogenicity data.
However, the study’s conclusions have sparked debate regarding clinical practice. Nick Zwar, chair of the smoking cessation guidelines expert advisory group for the Royal Australian College of General Practitioners, praised the review but cautioned against abandoning e-cigarettes entirely as a therapeutic aid.
“I don’t think this changes the message that nicotine vaping remains a reasonable therapeutic option when people have not succeeded with other methods,” Zwar noted.
The authors acknowledged that long-term, population-level epidemiological data for exclusive vapers does not yet exist. However, they emphasize that this gap reflects the relative novelty of widespread e-cigarette use rather than proof of its safety.
Source: https://www1.racgp.org.au/newsgp/clinical/vapes-likely-to-be-carcinogenic-study