Since the late 2000s, the introduction and rapid uptake of electronic cigarettes has provoked debate about their risks and potential benefits. The clinical and public-health communities remain divided: some emphasise e-cigarettes as a harm-reduction alternative to combustible tobacco, while others raise concerns about unknown long-term harms. The Comment summarises recent literature and highlights a new large database analysis that offers early data on lung cancer risk among people who quit smoking using vaping compared with those who quit without vaping.
Multiple overviews and systematic reviews have concluded that e-cigarettes can be an effective aid for smoking cessation. The Comment cites recent comprehensive reviews and systematic efforts that synthesise randomized and observational studies, indicating that nicotine vape products have shown effectiveness in helping some adults quit combustible cigarettes. The Cochrane review update and other contemporary analyses are referenced as sources supporting the effectiveness signal, though the Comment notes that the full evidence base continues to evolve.
The author highlights a recent, large database analysis by Kim et al. that examines lung cancer risk in individuals who quit smoking with e-cigarettes versus those who quit without e-cigarettes. Shields frames this study as providing a preliminary glimpse into comparative lung cancer risk across cessation methods rather than a definitive answer. Because this piece is a preview of subscription content, detailed methods, numerical results and subgroup analyses from Kim et al. are not reproduced in the Comment; readers are directed to the primary report for full data and interpretation.
A growing body of human studies has assessed biomarkers of exposure and early biological effects in vapers, smokers and non-smokers. Meta-analyses and individual studies cited include investigations of inflammatory and carcinogenic biomarker signatures, DNA methylation changes, and accelerated epigenetic age in lung tissue. These studies document alterations in biomarkers and gene expression associated with vaping that, in some instances, resemble changes seen with cigarette smoking. The Comment references these mechanistic and molecular data as important context for interpreting epidemiological findings, while noting that biomarker signals do not directly equate to quantified clinical cancer risk.
Population analyses and exposure studies have examined nicotine and toxicant exposure among individuals who use both combustible cigarettes and e-cigarettes. The Comment cites evidence showing heterogeneity of exposure based on level and pattern of product use, emphasising that dual use complicates attribution of risk to one product or another. These data underscore concerns that combining products may sustain or even increase exposure to nicotine and toxicants compared with exclusive cessation.
The Comment situates the vaping–lung cancer question within broader population-level work on lung cancer risk following smoking cessation. Studies that model absolute lung cancer risk over quit-years are relevant when determining surveillance and screening policies for former smokers, regardless of cessation method. The author references analyses used to inform guideline updates, reminding readers that absolute risk can change over time and that long-term follow-up is essential to evaluate cancer outcomes after quitting by different means.
Shields emphasises that although the literature provides signals from cessation trials, biomarker studies and observational analyses, the overall evidence on long-term lung cancer risk after quitting with e-cigarettes remains incomplete. The large database analysis by Kim et al. is described as an important contribution that offers an early view, but definitive conclusions require additional longitudinal data, transparent methods, and careful accounting for dual use and prior smoking intensity. The Comment calls for continued research combining epidemiology, mechanistic studies and policy-relevant modelling to clarify the continuum of harm.
The Comment is authored by Peter G. Shields. The author reports support from grant U54CA287392 from the National Cancer Institute and the FDA Center for Tobacco Products; the content is stated to be the author’s responsibility and does not necessarily represent official NIH or FDA views. The author declares no competing interests. The article appears as a subscription preview in Nature Reviews Clinical Oncology and cites the primary literature for readers seeking full datasets and analyses.