Lung cancer risks persist with e-cigarette use after quitting tobacco smoking

Key takeaways:

• Approximately 53,000 of about 4.3 million smokers developed lung cancer.
• The cohort also included 6,351 lung cancer-specific deaths.
• E-cigarettes include carbonyl compounds and toxic metals.

SAN DIEGO — Smokers who used electronic cigarettes after quitting had more risk for lung cancer than those who quit but did not use e-cigarettes, according to a study presented at the American Thoracic Society International Conference.

Although e-cigarettes have become a popular alternative to conventional tobacco smoking, their impact on lung cancer remains unclear, Yeon Wook Kim, MD, assistant professor, division of pulmonary and critical care medicine, department of internal medicine, Seoul National University Bundang Hospital, and colleagues wrote.

“This is the first large population-based study to demonstrate the increased risk of lung cancer in e-cigarette users after smoking cessation,” Kim said in a press release.

For example, the researchers said, e-cigarettes include some of the same carbonyl compounds and toxic metals that are known to be carcinogenic and are also found in conventional cigarettes.

The study comprised 4,329,288 people with a conventional smoking history who took part in the National Health Screening Program between 2012 and 2014 as well as in 2018, with follow-up through December 2021. The researchers stratified participants into six categories based on their smoking history and changes in habit.

The cohort included 53,354 people who developed lung cancer, with 6,351 lung cancer-specific deaths.

Former tobacco smokers reporting e-cigarette use 5 or more years after quitting were 2.69 (95% CI, 1.12-6.46) times more likely to experience a lung cancer-specific death than former tobacco smokers without e-cigarette use after 5 or more years or quitting.

Similarly, former tobacco smokers with e-cigarette use within less than 5 years of quitting were 1.23 (95% CI, 1.09-1.39) times more likely to develop lung cancer and 1.71 (95% CI, 1.1-2.66) times more likely to have a lung cancer-specific death than those without e-cigarette use with less than 5 years of quitting.

The researchers also specifically looked at participants aged 50 to 80 years with 20 or more pack-years of tobacco smoking, representing a population likely to be referred for low-dose lung cancer CT screenings based on 2021 U.S. Preventive Services Task Force and 2023 American Cancer Society guidelines.

Participants in this group with e-cigarette use within 5 or more years of quitting tobacco were 1.65 (95% CI, 1.05-2.58) times more likely to develop lung cancer and 4.46 (95% CI, 1.85-10.75) times more likely to experience a lung cancer-specific death than those in the group without e-cigarette use within 5 or more years.

Smokers who used e-cigarettes within 5 years of quitting in this group had a 1.26 (95% CI, 1.03-1.54) times greater risk for lung cancer than those who did not use e-cigarettes within 5 years of quitting.

Based on these findings, the researchers concluded that there was a greater risk for lung cancer and related mortality for smokers who use e-cigarettes after quitting tobacco, especially among those smokers who meet guidelines for screenings.

Also, the researchers said that clinicians should highlight these risks as part of their smoking cessation interventions to reduce risks for lung cancer among their patients.

“Our results indicate that when integrating smoking cessation interventions to reduce lung cancer risk, the potential harms of using e-cigarettes as an alternative to smoking must be considered,” Kim said.

Reference:

• Ex-cigarette smokers who vape may be at higher risk for lung cancer. https://site.thoracic.org/about-us/news/2024-international-conference-press-release/ex-cigarette-smokers-who-vape-may-be-at-higher-risk-for-lung-cancer. Published May 13, 2024. Accessed June 26, 2024.