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Former smokers who have switched to vaping may be at higher risk of lung cancer
Last reviewed: 02.07.2025
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Former cigarette smokers who use e-cigarettes or vaping devices may be at higher risk of developing lung cancer compared to those who do not vape, according to a study published at the ATS 2024 International Conference.
"This is the first large population-based study showing an increased risk of lung cancer in e-cigarette users after smoking cessation," said lead author Yeon Wook Kim, MD, associate professor, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Bundang Hospital, Republic of Korea.
E-cigarettes have gained popularity around the world as an alternative to smoking, and some smokers turn to vaping to help them quit. However, little is known about the long-term effects of vaping, and there is no epidemiological data on the link between e-cigarette use and lung cancer.
Biological studies suggest potential dangers of e-cigarettes, including lung toxicity and lung cancer. E-cigarettes and heating elements have been shown to contain carbonyl compounds (e.g., formaldehyde, acetaldehyde, acrolein, and diacetyl) and toxic metals (e.g., chromium, nickel, and lead), which are known carcinogens. These toxins are also present in regular cigarettes.
"Our findings suggest that the potential harmful effects of e-cigarette use as an alternative to smoking should be considered when integrating smoking cessation interventions to reduce lung cancer risk," said Dr. Kim.
To determine these people's risk, the researchers assessed 4,329,288 people with a history of regular smoking who participated in the National Health Screening Program of the Republic of Korea in two time periods: 2012–2014 and 2018. They conducted follow-up in December 2021.
The research team classified the participants into six groups based on their smoking history and habit change. They used statistical analysis to estimate the risk of developing lung cancer and dying from it in each group.
During follow-up, they found that 53,354 people developed lung cancer and 6,351 people died from lung cancer. Former cigarette smokers who quit smoking for five years or more and used e-cigarettes were at higher risk of dying from lung cancer than former smokers who quit smoking for five years or more and did not use e-cigarettes.
Among smokers who quit less than five years ago, those who used e-cigarettes had a higher risk of both developing lung cancer and dying from lung cancer compared with non-users of e-cigarettes.
Dr. Kim and colleagues also conducted a stratified analysis in which they looked at people aged 50–80 years with a smoking history of 20 or more pack-years, as these people are most likely to be referred for lung cancer screening according to the 2021 U.S. Preventive Services Task Force (USPSTF) recommendations and the 2023 American Cancer Society (ACS) guidelines.
Former smokers in this group who had quit smoking for five or more years and used e-cigarettes reported a higher risk of both lung cancer and death from lung cancer than those who did not use e-cigarettes. In addition, former smokers who used e-cigarettes and quit smoking less than five years ago had a higher comparative risk of developing lung cancer.
The authors conclude: "Clinicians should highlight the potentially harmful effects of e-cigarette use as an alternative when integrating smoking cessation interventions to reduce lung cancer risk."