Former cigarette smokers who use e-cigarettes may have a higher risk for lung cancer than those who do not vape, according to a study presented at the 2024 American Thoracic Society International Conference. Yeon Wook Kim, MD, and colleagues examined lung cancer risk and related mortality associated with smoking habit changes. The analysis included 4.3 million people with a conventional smoking history who participated in the National Health Screening Program from 2012 to 2014, with follow-up through 2021. Compared with ex-smokers with at least 5 years since quitting (YSQ) without e-cigarette use, those with e-cigarette use had an increased risk for lung cancer-specific death (aHR, 2.69). Similarly, ex-smokers with fewer than five YSQ with e-cigarette use had a higher risk for lung cancer development (aHR, 1.23) and lung cancer-specific death (aHR, 1.71) versus those without e-cigarette use. Among people 50 to 80 years of age with a smoking history of at least 20 pack-years, ex-smokers with at least five YSQ and e-cigarette use had a higher risk for lung cancer (aHR, 1.65) and lung cancer-specific death (aHR, 4.46) versus those without e-cigarette use.