A large study has found that former smokers who switch to e-cigarettes face substantially higher odds of dying from lung cancer than those who quit tobacco entirely. The research tracked more than 4.5 million adults in South Korea over several years. Experts say the findings underscore that complete cessation of both smoking and vaping offers the greatest protection.
Researchers led by Yeon Wook Kim at Seoul National University analyzed health data from participants in the Korean National Health Screening Programme between 2018 and 2023. They compared lung cancer outcomes among current smokers, short-term quitters, and long-term quitters, while also tracking self-reported e-cigarette use.
The study recorded 35,887 lung cancer cases and 12,807 related deaths. Ex-smokers who vaped showed a 56 percent higher risk of lung cancer death compared with those who stopped smoking without using e-cigarettes.
While vaping carried added risk, the overall death rate from any cause remained lower among ex-smokers who vaped than among people who continued smoking. Researchers stressed they could not establish direct causation and called for further studies outside South Korea.
Independent experts noted that safer quitting methods should be tried first, with e-cigarettes used only if other approaches fail. They added that switching to vaping is still less harmful than continued smoking.
