Former smokers who switch to vaping may be at higher risk of lung cancer

Former cigarette smokers who use e-cigarettes or vaping devices may be at higher risk of developing lung cancer compared with those who don't vape, according to a study published at the ATS 2024 International Conference.

"This is the first large population-based study to demonstrate an increased risk of lung cancer in e-cigarette users after smoking cessation," said lead author Yeon Wook Kim, MD, assistant professor, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Bundang National University Hospital, Republic of Korea.

E-cigarettes have gained popularity around the world as an alternative to regular smoking, and some smokers are turning to vaping to help quit smoking. However, little is known about the long-term effects of vaping, and epidemiological data on the link between e-cigarette use and lung cancer are lacking.

Biological studies suggest possible dangers of e-cigarettes, including lung toxicity and lung cancer. E-cigarettes and heating elements have been shown to contain carbonyl compounds (such as formaldehyde, acetaldehyde, acrolein, and diacetyl) and toxic metals (such as chromium, nickel, and lead), which are known carcinogens. These toxins are also present in regular cigarettes.

“Our findings suggest that when integrating smoking cessation interventions to reduce lung cancer risk, the potential harmful effects of using e-cigarettes as an alternative to smoking should be considered,” said Dr. Kim.

To determine the risk of these people, the researchers assessed 4,329,288 people with a history of habitual 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 changing habits. They used statistical analysis to estimate the risk of developing and dying from lung cancer 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 greater risk of dying from lung cancer than former smokers who quit smoking for five years or more and did not use e-cigarettes.

In smokers who quit less than five years ago, those who used e-cigarettes had a higher risk of both lung cancer and lung cancer mortality 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 pack-years or more, since these people are more likely to be referred for lung cancer screening according to 2021 US Preventive Services Task Force (USPSTF) guidelines and 2023 American Cancer Society (ACS) guidelines.

Former smokers in this group who had quit smoking for five years or more and used e-cigarettes reported a higher risk of both lung cancer and lung cancer death 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 emphasize the potentially harmful effects of e-cigarette use as an alternative when integrating smoking cessation interventions to reduce lung cancer risk.”