E-cigarette switching, smoking cessation, and the risk of hepatocellular carcinoma in patients with chronic hepatitis B: A nationwide cohort study in South Korea.

[OBJECTIVE] E-cigarettes (ECs) may reduce harm from combustible cigarettes (CCs), but their impact on hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) is unknown. We compared smoking cessation or EC switching versus continued smoking on HCC risk in CHB patients.

[METHODS] This retrospective cohort used Korean National Health Insurance data (2018-2023) on CHB patients who smoked at baseline. Participants were categorized as continued smokers (n = 86,338), quitters (n = 19,521), or EC switchers (n = 21,337). Secondary analysis included 83,540 with consistent behaviors.

[RESULTS] Over median follow-up of 4.93 years, 4184 developed HCC. Compared to continued CC smokers, both quitters (adjusted HR, 0.78; 95% CI, 0.70, 0.86) and ECs switchers (adjusted HR, 0.78; 95% CI, 0.70, 0.87) exhibited reduced HCC risk. Only 12% of EC switchers eventually quit smoking while 61% of initial quitters remained quit at follow-up. Persistent quitters showed greater HCC risk reduction (adjusted HR, 0.64; 95% CI, 0.52, 0.77) than persistent CCs-to-ECs switchers (adjusted HR, 0.73; 95% CI, 0.59, 0.89), though not significant.

[CONCLUSIONS] Complete tobacco cessation should remain the primary strategy given superior behavioral sustainability, with no significant difference in HCC risk reduction versus EC switching.