Former smokers who switched to daily e-cigarette use had a 56 percent higher risk of lung cancer than former smokers who gave up nicotine altogether. The risk of dying from the disease was twice as high. Those are the headline results of a South Korean study published in Nature Medicine.
Researchers at Seoul National University Bundang Hospital, led by Professor Kim Yeon-wook of the Department of Pulmonology and Critical Care Medicine, analyzed records for 4,524,895 Korean adults with a history of smoking. All had taken part in the National Health Screening Program in 2018, and the team also reviewed their health examination records from 2012 to 2014.
Between quitting and smoking
Vaping did not look as bad as smoking. Participants who kept smoking conventional cigarettes had a 1.78-fold higher risk of lung cancer and a 2.41-fold higher risk of dying from it, compared with those who quit everything. The vapers sat in between.
Among adults aged 50 to 80 with at least 20 pack-years of smoking history, a group at high risk for the disease, the gap widened. Those who switched to e-cigarettes had a 1.91-fold higher risk of developing lung cancer and a 1.92-fold higher risk of dying from it than those who quit all tobacco products.
“Many people who switch from conventional cigarettes to e-cigarettes believe they have quit smoking,” Kim said. “While e-cigarettes may pose a lower risk than conventional cigarettes in terms of lung cancer, they still expose users to harmful substances and should be regarded as a form of smoking. Complete smoking cessation remains the best option for reducing health risks.”
What the study can and cannot say
Prof. Elizabeth Dudnik, head of thoracic oncology at Assuta Medical Centers in Israel, described the findings for Ynet. Former smokers who kept using e-cigarettes had a 22 percent higher risk of death from any cause than former smokers who did not, she said. Compared with active smokers, former smokers without e-cigarettes had a 44 percent lower risk of lung cancer. For those who kept vaping, the reduction shrank to 12 percent.
The researchers tested whether the pattern came from differences between the groups. They checked for recent quitters, heavier past smoking and poorer baseline health, and excluded cancers diagnosed in the first year of follow-up. The results stayed similar. The link was also stronger among people who had stopped smoking more than five years earlier.
Dudnik was careful about what that proves. “The study does not prove that e-cigarettes cause lung cancer,” she said. “Rather, it indicates that using them after quitting smoking may reduce some of the health benefits of cessation.” The authors of a commentary in Nature Medicine said the same, adding that vaping products may promote cancerous processes that have already begun. They called for more research on long-term biological effects.
A separate study of 179,273 former smokers in South Korea, published in the American Journal of Ophthalmology, found a 24 percent higher risk of diabetic retinopathy among those who switched to e-cigarettes than among those who stopped nicotine entirely. It is observational and does not establish cause.
“The ultimate goal should be complete cessation of smoking and nicotine use, with professional guidance and treatments that have been proven effective,” Dudnik said.
Sources
- Former smokers who vape face higher lung cancer and death risks, study finds
- Switching to e-cigarettes after quitting smoking linked to higher lung cancer risk than complete cessation
