A study found that among people with chronic hepatitis B, those who quit smoking had a 22% lower risk of developing hepatocellular carcinoma than those who kept smoking conventional cigarettes.
Hepatocellular carcinoma is the most common primary liver cancer that arises in the liver, and chronic hepatitis B is one of the main risk factors. In this study, even those who switched from conventional cigarettes to e-cigarettes had a 22% lower risk of hepatocellular carcinoma. However, the risk in the e-cigarette switch group was not lower than in the quit-smoking group.
Researchers at Samsung Medical Center and Sungkyunkwan University analyzed the association between changes in smoking status and the risk of hepatocellular carcinoma in people with chronic hepatitis B using National Health Insurance data, and published the findings in the international journal "Preventive Medicine."
The study included Song Byung-geun, assistant professor; Kwak Geum-yeon, professor; and Shin Dong-hyun, professor, in the Division of Gastroenterology at Samsung Medical Center, and Professors Lee Myung-chul, Cho Ju-hee, and Kang Dan-bi in the Department of Clinical Research Design and Evaluation at Sungkyunkwan University.
The team analyzed 127,196 people with chronic hepatitis B who had a history of smoking at baseline, drawn from National Health Insurance data from 2018 to 2023. Participants were classified into 86,338 who continued smoking conventional cigarettes, 19,521 who quit, and 21,337 who switched from conventional cigarettes to e-cigarettes.
The median follow-up was 4.93 years, during which hepatocellular carcinoma occurred in 4,184 people.
After adjusting for relevant factors such as age, sex, and smoking amount, the risk of hepatocellular carcinoma was 22% lower in the quit-smoking group compared with the group that continued smoking conventional cigarettes. The adjusted hazard ratio (aHR) was 0.78. The adjusted hazard ratio compares disease risk between two groups after accounting for other factors; 0.78 means the group's risk is 0.78 times that of the reference group, whose risk is set at 1.
The adjusted hazard ratio in the e-cigarette switch group was also 0.78, indicating a 22% lower risk of hepatocellular carcinoma than in the group that continued smoking conventional cigarettes. However, because this was a retrospective cohort study, it does not prove a causal relationship that quitting smoking or switching to e-cigarettes directly reduces the risk of hepatocellular carcinoma.
The researchers conducted an additional analysis of 83,540 people who maintained their smoking behavior consistently. In this analysis, those who consistently remained abstinent had a 36% lower risk of hepatocellular carcinoma than the group that continued smoking conventional cigarettes (aHR 0.64), and those who consistently remained switched to e-cigarettes had a 27% lower risk (aHR 0.73). Although the risk reduction was greater in the quit-smoking group, the difference between the two groups was not statistically significant.
There was a difference in maintaining smoking behavior. Only 12% of those who switched to e-cigarettes later quit completely, but 61% of those who initially quit remained abstinent at follow-up. About 37% of those who switched to e-cigarettes later returned to conventional cigarettes.
The researchers said, "In smoking management for people with chronic hepatitis B, complete cessation should be prioritized over switching to e-cigarettes."
References
Preventive Medicine (2026), DOI: https://doi.org/10.1016/j.ypmed.2026.108530