For ex-smokers who reach for a vape, the trade may not be as clean as the marketing implies. In the largest population study to date on the question, adults who used e-cigarettes after quitting conventional cigarettes carried a measurably higher lung-cancer risk than peers who quit outright.
Published June 8 in Nature Medicine, the study drew on 4,524,895 adults with a conventional smoking history enrolled in the Korean National Health Screening Program in 2018, with prior records from 2012–2014. Participants were classed as current smokers, short-term quitters or long-term quitters, and daily e-cigarette use at baseline defined post-cessation vaping. Researchers tracked lung-cancer incidence and lung-cancer-specific death through December 2023 using multivariable Cox models.
What the numbers show
Across 24,182,543 person-years, 35,887 lung cancers and 12,807 lung-cancer-specific deaths occurred. Compared with complete quitters, post-cessation e-cigarette users had an adjusted hazard ratio of 1.56 (95% CI 1.24–1.97) for lung-cancer incidence and 2.00 (95% CI 1.28–3.15) for lung-cancer death. The association held in both short- and long-term quitters and was strongest in a high-risk subgroup (incidence aHR 1.91, 95% CI 1.44–2.53).
“These findings suggest that e-cigarette use after smoking cessation may attenuate the benefits of complete cessation for lung cancer prevention,” the authors write.
Two caveats matter. This is an observational cohort, so association is not causation — the authors state plainly that causality cannot be established, and residual confounding by smoking intensity or duration is hard to fully rule out. And vaping status was measured only at baseline. Still, at this scale, the signal is hard to dismiss: trading cigarettes for a vape may not erase the cancer risk that quitting does.