The current Cancer Research UK position is explicit: “There is no good evidence that vaping causes cancer”. Vape produces no combustion (no PAHs), contains no tobacco leaf (no tobacco-specific N-nitrosamines or TSNAs), has far fewer chemicals overall than cigarette smoke (4-10 main compounds versus 7000+), and produces no tar or carbon monoxide. Public Health England’s 2015 estimate that vape is around 95% less harmful than smoking remains the foundation of UK NHS policy on vape as a smoking cessation tool. This figure is widely cited in UK Government Tobacco Control Plan documents.

However, vape is not 100% safe and long-term studies are still emerging. The most recent comprehensive evidence is the 2025 ESMO Open systematic review (Ghose et al., Barts Cancer Institute, Queen Mary University of London and Cancer Research UK City of London Centre), which examined PubMed, Cochrane Library, Embase, ScienceDirect, Web of Science, Scopus and Google Scholar studies up to June 2024. Key findings: no significant incident or prevalent lung cancer risk in never-smokers who currently vape; however, biomarker-based studies, cell/in vitro and animal studies indicate e-cigarette exposure can cause oxidative stress, DNA damage, genotoxicity and tumour growth markers.

The highest cancer risk pattern is dual use (vaping plus continuing to smoke cigarettes). A large case-control study by Bittoni et al. observed that vaping combined with chronic smoking elevated the risk of lung cancer 4x higher than chronic cigarette smoking alone. This dual-use pattern was 8x more common among lung cancer patients than controls. The takeaway for UK vapers: switch completely from smoking to vape, don’t dual-use. For ex-smokers who have completely switched, the cancer risk profile is dramatically improved versus continued smoking. For never-smokers, vape carries unquantified long-term cancer risk and NHS guidance is that never-smokers should not vape recreationally.

Why vape is much lower cancer risk than smoking

Three main reasons. First, no combustion: vape heats e-liquid to vapour at 200-250 degrees Celsius, far below the 600-900 degrees of tobacco combustion. Combustion is what produces polycyclic aromatic hydrocarbons (PAHs), the largest single class of smoking carcinogens. Without combustion, no PAHs. Second, no tobacco: vape contains nicotine extracted from tobacco but not tobacco leaf itself. Tobacco-specific N-nitrosamines (TSNAs), the second major class of smoking carcinogens, are largely absent from TPD-compliant UK vape products. Third, fewer chemicals overall: cigarette smoke contains 7000+ compounds with 69+ confirmed carcinogens; vape vapour contains around 4-10 main compounds plus flavour molecules. Cancer Research UK consistently emphasises that vape is far less harmful than smoking precisely because of these structural differences in chemistry.

What the cell and animal studies show (and don’t)

A significant body of research has examined whether vape exposure causes cancer-relevant cellular changes. The 2025 ESMO Open systematic review summarised this evidence: in vitro (cell) studies and animal models show e-cigarette exposure can cause oxidative stress, cellular apoptosis, DNA damage, genotoxicity and increased tumour growth markers. A 2023 study found exclusive vapers exhibited DNA damage in oral epithelial cells comparable to smokers, with damage increasing with frequency and flavour type. A single vaping session can cause measurable increases in bodily inflammation (one study reported 30% increase in oxidative stress markers). However, these findings are at the cellular and biomarker level, not at the clinical cancer outcomes level. The 2025 review specifically noted that no human studies have yet shown significant lung cancer or other cancer incidence in never-smoker current vapers. Most cellular studies focus on acute exposure findings, leaving short-to-medium and long-term cancer risk from chronic vape exposure unknown.

Why the dual-use pattern is the worst

Dual use (continuing to smoke while also vaping) carries the highest cancer risk, higher than either smoking alone or vaping alone. Three factors combine. First, additive carcinogen exposure: dual users get all the cigarette smoke carcinogens plus all the vape exposure simultaneously. Second, behavioural pattern: dual users typically smoke when convenient and vape when smoking is restricted (work, public spaces), meaning they maintain or even increase total daily nicotine intake compared with smoking alone. Third, biological synergy: some emerging research suggests interactions between vape and cigarette chemicals may produce more cellular damage than either alone. The Bittoni et al. case-control study found dual users had 4x higher lung cancer risk than chronic smokers alone, and the dual-use pattern was 8x more common in lung cancer patients than controls. NHS Stop Smoking Service guidance: if you are using vape to help quit smoking, the goal is complete switch, not parallel use. UK Stop Smoking advisors specifically address dual use as the pattern to avoid.

For UK vapers concerned about cancer risk, the four-step framework below reflects current Cancer Research UK and NHS guidance based on the latest evidence.

For UK ex-smokers who switched to vape, the cancer risk reduction versus continued smoking is significant and well-established. Cancer Research UK explicitly recommends vape as a smoking cessation tool. For UK never-smokers, the NHS, Cancer Research UK and Public Health England all advise against starting vape recreationally. The long-term studies needed to fully quantify vape cancer risk over 20-30 years of chronic use are still in progress; current evidence supports vape as a smoking cessation tool but not as a recreational habit. Our Omagh and Strabane teams only sell TPD-compliant products from registered UK suppliers and can advise on cessation pathways.