science
Study of 4.5 million finds higher lung cancer death risk among vaping ex-smokers
A South Korean study tracked more than 4.5 million adults and found that former smokers who used e-cigarettes had a 56 percent higher risk of dying from lung cancer than those who quit without vaping. The same data showed that any form of quitting still lowered overall death risk compared with continued smoking.
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A study of more than 4.5 million adults who took part in South Korea's national health screening program from 2018 to 2023 recorded 35,887 lung cancer cases and 12,807 related deaths. Researchers divided participants into current smokers, short-term quitters, and long-term quitters, then compared outcomes according to self-reported e-cigarette use.
Former smokers who vaped showed a 56 percent higher risk of lung cancer death than those who quit without vaping. The same analysis found that overall death risk remained lower among ex-smokers who vaped than among people who continued smoking.
Study limitations and context Researchers stated they could not prove vaping itself caused the added cancer risk and called for longer studies that include populations outside South Korea. Some chemicals in e-cigarettes have been linked in separate work to DNA damage, oxidative stress, and inflammation in lung tissue.
More than 40 percent of people in the United Kingdom who quit smoking in 2024 reported using e-cigarettes, and one in five continued vaping a year later.
Expert reactions An Australian researcher not involved in the study said the findings add to evidence that e-cigarettes carry risks beyond those initially claimed and recommended trying other cessation methods first. A second Australian expert said switching to vaping remains safer than continued smoking, though complete cessation of both products offers the greatest protection.
